by William G. Walant*

The Fourth Amendment’s “rea­son­able­ness clause” pro­vides that cit­i­zens have a right “to be secure in their per­sons, hous­es, papers, and effects, against unrea­son­able search­es and seizures[.]”1 Courts gen­er­al­ly ask two ques­tions in deter­min­ing if a Fourth Amend­ment vio­la­tion has occurred: (1) whether the alleged gov­ern­ment con­duct con­sti­tutes a “search” with­in the mean­ing of the Fourth Amend­ment, and (2) whether the search was “rea­son­able.”2

As to the first ques­tion, a search impli­cates the Fourth Amend­ment if it frus­trates an individual’s “rea­son­able expec­ta­tion of pri­va­cy”3 or if it con­sti­tutes a tres­pass done “for the pur­pose of obtain­ing infor­ma­tion.”4,5 But this con­sti­tu­tion­al pro­tec­tion against unrea­son­able search­es does not apply to a non-gov­ern­ment party’s search.6 If such pri­vate par­ty does com­mence a search and presents the find­ings to the police, the police are under no oblig­a­tion to “avert their eyes.”7 It is with these prin­ci­ples in mind that the “pri­vate search doc­trine” was born: a gov­ern­ment intru­sion sub­se­quent to a pri­vate party’s intru­sion is not a search under the mean­ing of the Fourth Amend­ment if the gov­ern­ment has “vir­tu­al cer­tain­ty” that the search will expose no more than what the pri­vate party’s ear­li­er intru­sion had revealed.8

The Supreme Court has not addressed how the pri­vate search doc­trine applies to a present-day elec­tron­ic media stor­age device (“EMSD”), such as a smart phone or a flash dri­ve. Indeed, the Court has not ruled direct­ly on the doc­trine since the 1980s.9 How­ev­er, in Riley v. Cal­i­for­nia,10 the Court made clear that smart phones impli­cate sub­stan­tial pri­va­cy inter­ests.11 As a result, the Court sub silen­tio made a per se rule: regard­less of whether a pri­vate search pre­cedes a gov­ern­ment search, an offi­cer must obtain a war­rant to search a smart phone.12 Still, the water is murki­er for devices that are not as obvi­ous­ly per­va­sive in our lives or per­son­al­ly reveal­ing as smart phones. Specif­i­cal­ly, EMS­Ds such as flash dri­ves, ZIP dri­ves, and flop­py disks are per­fect use-cas­es to explore the out­er-bounds of Riley and the pri­vate search doc­trine because they are more lim­it­ed in phys­i­cal size and mem­o­ry stor­age than mobile phones, they are gen­er­al­ly uncon­nect­ed to the inter­net, and they usu­al­ly require that a par­ty actu­al­ly move or copy files onto the device.

With­out clear guid­ance from the Supreme Court, the cir­cuits that have ruled on this issue are split. The Fifth and Sev­enth Cir­cuits have adopt­ed a “broad” approach by analo­giz­ing EMS­Ds to closed con­tain­ers: if a pri­vate par­ty opens the EMSD (read: “closed con­tain­er”) and if the offi­cers are sub­stan­tial­ly cer­tain as to the rest of the con­tents in the EMSD, then the offi­cers can view those con­tents regard­less of whether or not the pri­vate par­ty has already viewed them.13 For exam­ple, in Unit­ed States v. Run­yan,14 pri­vate par­ties had col­lect­ed flop­py disks, CDs, and ZIP disks of the defen­dant. They only par­tial­ly exam­ined some of the flop­pies and CDs, where they saw child pornog­ra­phy, but did not view any of the ZIPs.15 Police offi­cers were hand­ed these disks and viewed all of them in their entire­ty.16 While the Fifth Cir­cuit found that view­ing the pre­vi­ous­ly com­plete­ly unex­am­ined ZIPs, flop­pies, and CDs did exceed the pri­vate search doc­trine, it also held that the offi­cers did not exceed the doc­trine when they viewed all of the files on the pre­vi­ous­ly par­tial­ly exam­ined flop­pies and CDs, which it called “closed con­tain­ers,” because they were sub­stan­tial­ly cer­tain as to their con­tents.17 In short, “the police do not exceed the pri­vate search when they exam­ine more items with­in a closed con­tain­er than did the pri­vate searchers.”18

Sim­i­lar­ly, in Rann v. Atchi­son,19 a pri­vate par­ty brought the defendant’s cam­era mem­o­ry card and com­put­er zip dri­ve that had child pornog­ra­phy to the police. Because the par­ties brought this evi­dence to sup­port alle­ga­tions of child pornog­ra­phy, the Sev­enth Cir­cuit found it rea­son­able to con­clude that the offi­cers knew the devices con­tained child pornog­ra­phy.20 As to the offi­cers’ sub­se­quent search, rely­ing on Run­yan,21 the court said that even if the police more thor­ough­ly searched the dig­i­tal media devices than [the pri­vate par­ties], . . . the police search did not exceed or expand the scope of the ini­tial pri­vate search­es. Because [the pri­vate par­ties] knew the con­tents of the dig­i­tal media devices when they deliv­ered them to the police, the police were “sub­stan­tial­ly cer­tain” the devices con­tained child pornog­ra­phy.22

Oth­er courts, such as the Sixth and Eleventh Cir­cuits and the Unit­ed States Court of Appeals for the Armed Forces, have instead adopt­ed a “nar­row­er” approach than the Fifth and Sev­enth Cir­cuits.23 As more ful­ly illus­trat­ed below, these courts rec­og­nize the spe­cial issues that tech­nol­o­gy rais­es in the Fourth Amend­ment con­text, so, depend­ing on the device at-hand, “the scope of the pri­vate search can be mea­sured by what the pri­vate actor actu­al­ly viewed as opposed to what the pri­vate actor had access to view.”24

For instance, in Unit­ed States v. Licht­en­berg­er,25 a pri­vate par­ty hacked into the defendant’s lap­top and clicked on dif­fer­ent fold­ers, where she saw images of sex acts with minors. When the police arrived, she ran­dom­ly clicked on a few of the images, about four or five, but told the offi­cer she had viewed about one hun­dred.26 Although the case involved a lap­top, rather than the type of EMSD direct­ly addressed by this Con­tri­bu­tion, the Sixth Cir­cuit court rea­soned that the pri­vate search doc­trine was vio­lat­ed by broad­ly assert­ing that “search­es of phys­i­cal spaces and the items they con­tain dif­fer in sig­nif­i­cant ways from search­es of com­plex elec­tron­ic devices under the Fourth Amend­ment. . . . The real­i­ty of mod­ern data stor­age is that the pos­si­bil­i­ties are expan­sive.”27

Indeed, three years after Licht­en­berg­er, the Sixth Cir­cuit was pre­sent­ed with a case involv­ing the type of EMS­Ds addressed in this Con­tri­bu­tion in Unit­ed States v. Chap­man-Sex­ton.28 There, the police recov­ered a stolen flash dri­ve and PlaySta­tion of the defen­dant, and, upon learn­ing from a third-par­ty that the devices con­tained child pornog­ra­phy, looked at three images on the flash dri­ve.29 While the major­i­ty did not direct­ly address the pri­vate search doc­trine because it opt­ed to instead rule based on the “inevitable dis­cov­ery” doc­trine,30 Judge John Bush not­ed in his con­cur­ring opin­ion that “[o]ne could argue that Licht­en­berg­er’s rea­son­ing extends (though it did not explic­it­ly say so) to all elec­tron­ic devices” and so he could “not say that the pri­vate-search doc­trine is nec­es­sar­i­ly sat­is­fied here based on our circuit’s prece­dent.”31

Sim­i­lar­ly, in the Eleventh Cir­cuit case Unit­ed States v. Sparks,32 an offi­cer received a cell phone from pri­vate par­ties who had clicked on some of its stored images. One of the pri­vate par­ties scrolled through the entire­ty of the album for the offi­cer and showed just one of the videos, but the offi­cer sub­se­quent­ly viewed anoth­er video on the phone.33 The Eleventh Cir­cuit con­clud­ed that the officer’s sub­se­quent, more thor­ough exam­i­na­tion of the images they were shown did not vio­late the pri­vate search doc­trine.34 How­ev­er, since the pri­vate par­ty had not viewed all of the videos, nor shown all of them to the offi­cer, the officer’s lat­er war­rant­less inspec­tion of the oth­er video vio­lat­ed the pri­vate search doc­trine and thus con­sti­tut­ed a search.35


The Sixth and Eleventh Circuit’s nar­row approach bet­ter com­ports with the log­i­cal and legal under­pin­nings of the pri­vate search doc­trine. In the con­text of an EMSD, the pri­vate search doc­trine requires that a gov­ern­ment actor stay with­in the con­fines of what the pri­vate par­ties actu­al­ly viewed. Although offi­cers may legal­ly exceed those con­fines if they are so cer­tain as to the con­tents of the item that their search would only pro­vide con­fir­ma­tion of what the pri­vate par­ty had relayed to them, in the con­text of EMS­Ds, those sit­u­a­tions are few and far between—and can­not come about by mere par­tial expo­sure of some of an EMSD’s con­tents. As explained more ful­ly below, the Sixth and Eleventh Cir­cuits rec­og­nize these lim­i­ta­tions and thus have the bet­ter of the two approaches.

First, the pri­vate search doc­trine is ground­ed in the “plain view doc­trine,”36 so, con­trary to what the Fifth and Sev­enth Cir­cuits sug­gest, a par­tial inva­sion by a pri­vate par­ty gen­er­al­ly can­not jus­ti­fy an officer’s sub­se­quent full inva­sion. Under the plain view doc­trine, a per­son has no rea­son­able expec­ta­tion of pri­va­cy over that which is exposed to the pub­lic; if it has not been exposed, then any rea­son­able expec­ta­tion of pri­va­cy that exists is pre­served.37 Accord­ing­ly, in terms of the pri­vate search doc­trine, if a pri­vate search “mere­ly frustrate[s] that expec­ta­tion in part,” then a “par­tial inva­sion can­not auto­mat­i­cal­ly jus­ti­fy a total inva­sion.”38 This rea­son­ing must be the case—for the doc­trine to mean any­thing oth­er­wise would cre­ate an arbi­trary dou­ble stan­dard, where­by a war­rant requires par­tic­u­lar­i­ty, but a war­rant­less search is lim­it­less as long as it is in some way ini­ti­at­ed by a pri­vate per­son.39

Offi­cers can exceed what has already been exposed or viewed,40 but only under very spe­cif­ic cir­cum­stances,41 which leads to the sec­ond point: those cir­cum­stances are much more lim­it­ed than the Fifth and Sev­enth Cir­cuits acknowl­edge. When the gov­ern­ment is able to exceed what was lit­er­al­ly viewed dur­ing a pri­or pri­vate search, it may do so only if “there was vir­tu­al cer­tain­ty that [fur­ther inspec­tion] . . . would not tell [the offi­cer] any­thing more than he had already been told.”42 This “vir­tu­al” or “sub­stan­tial” cer­tain­ty require­ment is meant to be extreme­ly nar­row. For instance, in Jacob­sen, even though FedEx employ­ees had only seen white pow­der in a bag after they opened a box, the offi­cers went fur­ther by ana­lyz­ing the white pow­der. Yet, the Court found that because the drug test could only ver­i­fy whether the pow­der was cocaine, “the like­li­hood that offi­cial con­duct of the kind dis­closed by the record will actu­al­ly com­pro­mise any legit­i­mate inter­est in pri­va­cy seems much too remote to char­ac­ter­ize the test­ing a search sub­ject to the Fourth Amend­ment.”43 In reach­ing this deter­mi­na­tion, the Court cit­ed Unit­ed States v. Place,44 where­in the use of a canine to sniff for nar­cotics in lug­gage at an air­port was found to not be a search in part because “[i]t d[id] not expose non­con­tra­band items that oth­er­wise would remain hid­den from pub­lic view.”45

The Sixth and Eleventh Cir­cuits’ nar­row approach to EMS­Ds best com­ports with those two under­ly­ing prin­ci­ples. First, as rec­og­nized by these Cir­cuits, EMS­Ds have the poten­tial to hold vast­ly more infor­ma­tion than tra­di­tion­al phys­i­cal con­tain­ers, there­by rais­ing the prob­a­bil­i­ty that an offi­cer will intrude upon pre­vi­ous­ly unviewed pri­vate infor­ma­tion.46 An aver­age flop­py disk can hold 1.44 megabytes of stor­age47 and a typ­i­cal CD can hold 700 megabytes; com­par­a­tive­ly, some of the small­est flash dri­ves on the mar­ket hold 64,000 megabytes and some of the largest reach 1,000,0000 megabytes.48 It is thus intel­lec­tu­al­ly disin­gen­u­ous to sim­ply analo­gize EMS­Ds to “con­tain­ers,” as the Fifth and Sev­enth Cir­cuits have done—EMSDs are more like con­tain­ers with nest­ing dolls of oth­er con­tain­ers that each, in turn, hold nest­ing dolls of still more con­tain­ers. Indeed, a hard dri­ve itself has been described as “simul­ta­ne­ous­ly [a] file cab­i­net[] (with mil­lions of files) and [a] locked desk draw­er[]; [it] can be repos­i­to­ries of inno­cent and deeply per­son­al infor­ma­tion.”49 The like­li­hood that a legit­i­mate pri­va­cy inter­est will be com­pro­mised dur­ing the exam­i­na­tion of an EMSD’s con­tents is, bor­row­ing from the words of Jacob­sen, not so “remote” as to avoid being char­ac­ter­ized a search under the Fourth Amend­ment.50

More­over, the nar­row approach rec­og­nizes the height­ened pri­va­cy inter­ests inhered in the con­tent of EMS­Ds. EMSDs—and the devices they con­nect to, such as computers—have grown sub­stan­tial­ly more per­son­al as they have become per­va­sive sta­ples in our lives.51 This nuance fur­ther rais­es the prospect that the infor­ma­tion an offi­cer will intrude upon will be among an individual’s most sen­si­tive.52 It there­fore can­not (and should not) be the case that the gov­ern­ment stays with­in the con­fines of the pri­vate search doc­trine if an offi­cer can exam­ine the entire­ty of an EMSD mere­ly on the grounds that a pri­vate par­ty par­tial­ly viewed its con­tents and the offi­cer searched “more thor­ough­ly” than the pri­vate par­ty.53 Fur­ther, the per­va­sive­ness of EMS­Ds means that they will hold a more wide and var­ied col­lec­tion of per­son­al infor­ma­tion than most tra­di­tion­al, phys­i­cal items, which lessens the chance that an offi­cer can draw more than an infer­ence as to their con­tents based on a pri­vate party’s mere par­tial view­ing.54


The nar­row approach advo­cat­ed by this Con­tri­bu­tion is not with­out its faults. As explained in more detail below, first, EMS­Ds arguably do not pose the same pri­va­cy con­cerns as com­put­ers or smart phones, espe­cial­ly giv­en that EMS­Ds are usu­al­ly not con­nect­ed to the inter­net and their con­tents are often fil­tered by a pri­vate par­ty. Sec­ond, the nar­row approach seems to cre­ate an extreme­ly fact-spe­cif­ic cri­te­ri­on that will be too oner­ous for courts to apply, arguably sug­gest­ing that we should just aban­don the pri­vate search doc­trine as we know it and ful­ly pro­hib­it, with some excep­tions, war­rant­less gov­ern­ment search­es of EMS­Ds. Third, and in the same vein, the nar­row approach might under­cut expe­di­tious inves­ti­ga­tions or result in arbi­trary line-draw­ing tasks for courts. This Con­tri­bu­tion will now address each of these objec­tions, in turn. As dis­cussed more ful­ly below, these con­cerns are at worst, non-fatal, and at best, illusory.

It is true that EMS­Ds do not pose exact­ly the same pri­va­cy con­cerns as com­put­ers or smart phones. For instance, unlike the smart phone in Riley, EMS­Ds are usu­al­ly not con­nect­ed to the inter­net. How­ev­er, this dif­fer­ence only mat­ters in degree, not in kind. First, Riley was a con­sol­i­da­tion of two cas­es, one of which involved an old­er mod­el cell phone that did not have the same inter­net con­nec­tiv­i­ty fea­tures as the new­er smart phone55—a dis­tin­guish­ment nary men­tioned by the Court. Sec­ond, the Court repeat­ed­ly empha­sized that elec­tron­ic devices like com­put­ers increase the pri­va­cy inter­ests at stake because of their stor­age capac­i­ty—sep­a­rate and apart from whether they are con­nect­ed to the inter­net.56 As not­ed above, EMS­Ds like flash dri­ves clear­ly raise stor­age capac­i­ty issues both in the amount of infor­ma­tion they can hold and in the amount of per­son­al and unre­lat­ed files they will like­ly con­tain, albeit not nec­es­sar­i­ly to the same extent as com­put­ers or smart phones.57

It is also true that EMS­Ds gen­er­al­ly require copy­ing files from a source, such as a com­put­er. As a result, the con­tents of an EMSD are arguably fil­tered or curat­ed by a pri­vate par­ty and, in turn, the expec­ta­tion of pri­va­cy in those con­tents are frus­trat­ed or dimin­ished by the time an offi­cer receives the EMSD.58 Indeed, the Court has on numer­ous occa­sions declined to con­strain an officer’s abil­i­ty to con­duct a war­rant­less search of a con­tain­er when an expec­ta­tion of pri­va­cy in that con­tain­er has already been frus­trat­ed or dimin­ished.59 How­ev­er, per Jacob­sen, what mat­ters in the con­text of the pri­vate search doc­trine is the rea­son­able­ness of the officer’s search at the time that the offi­cer made the intru­sion, which can depend upon what infor­ma­tion the pri­vate par­ty had relayed to the offi­cer.60 Regard­less of the fact that a pri­vate par­ty has copied files onto the dri­ve, if they have made no assur­ance that an EMSD only con­tains files they have actu­al­ly viewed, an offi­cer can­not be suf­fi­cient­ly cer­tain that a sub­se­quent search will avoid untouched pri­va­cy inter­ests because of the unique nature of EMS­Ds.61

As explained more ful­ly below, the sce­nario where a pri­vate par­ty, unin­flu­enced and unco­erced, makes a rep­re­sen­ta­tion such that an offi­cer has suf­fi­cient cer­tain­ty to sat­is­fy the pri­vate search doc­trine for an EMSD is very lim­it­ed.62 Some recent schol­ar­ship has thus argued that the Supreme Court should sim­ply “exempt” EMS­Ds from the pri­vate search doc­trine altogether—that is, the Court would cat­e­gor­i­cal­ly deem EMS­Ds unsearch­able absent a war­rant or oth­er excep­tion, so the doc­trine would nev­er apply to EMS­Ds.63 How­ev­er, cre­at­ing such an exemp­tion is unnec­es­sary. EMS­Ds can fit nice­ly into the pri­vate search doc­trine and cre­ate a social­ly desir­able out­come because the nar­row approach effec­tive­ly cre­ates a per se rule: absent an unusu­al cir­cum­stance, “it [would be] vir­tu­al­ly impos­si­ble for law enforce­ment to be suf­fi­cient­ly cer­tain of what they will find upon the dig­i­tal device.”64 As a result, in almost every case, the offi­cer will not be able to exam­ine the EMSD with­in the con­fines of the pri­vate search doc­trine and thus will be required to obtain a warrant.

In fact, the nar­row approach to the pri­vate search doc­trine actu­al­ly encour­ages offi­cers to seek war­rants or, at the very least, per­form basic inves­tiga­tive due dili­gence65 when review­ing an EMSD hand­ed over by a pri­vate party—even if a pri­vate par­ty rep­re­sents that they have viewed every file in the EMSD. A rea­son­able offi­cer, ceteris paribus, would like­ly pre­fer to guar­an­tee admit­tance of evi­dence ex ante, as opposed to risk sup­pres­sion and fight for admit­tance ex post.66 An offi­cer could gam­ble and not per­form any inves­tiga­tive dili­gence of a pri­vate party’s rep­re­sen­ta­tion, but giv­en the nature of EMS­Ds and the nar­row approach, there is a high chance that the offi­cer will come upon new infor­ma­tion and a court will sup­press such evi­dence. If the offi­cer per­forms due dili­gence and does not come upon new con­tent, then the pri­vate search doc­trine has worked as it should; how­ev­er, ex ante, there is still a high risk that the offi­cer will come upon new con­tent dur­ing the due dili­gence that will lat­er be sup­pressed. Tak­ing stock of all these steps, this lack of cer­tain­ty67 would like­ly encour­age offi­cers to seek a warrant.

Encour­ag­ing war­rants is, of course, a social­ly desir­able out­come. A cen­tral pur­pose of the Fourth Amend­ment is to pro­tect pri­va­cy,68 which is most effec­tive­ly achieved when gov­ern­ment search­es are medi­at­ed by a neu­tral mag­is­trate.69 “Over and again this Court has empha­sized that the man­date of the (Fourth) Amend­ment requires adher­ence to judi­cial process­es, and that search­es con­duct­ed . . . with­out [a war­rant] are per se unrea­son­able under the Fourth Amendment—subject only to a few specif­i­cal­ly estab­lished and well-delin­eat­ed excep­tions.”70

Still, the nar­row approach as applied to dig­i­tal infor­ma­tion might impose strin­gent and unre­al­is­tic guide­lines on gov­ern­ment agents.71 Effec­tive­ly requir­ing an offi­cer to sit down with a pri­vate par­ty to review each and every file or to obtain a war­rant could slow down inves­ti­ga­tions that need to be swift­ly com­plet­ed. How­ev­er, the Supreme Court has nev­er sac­ri­ficed the war­rant require­ment sim­ply because an inves­ti­ga­tion might be slowed.72 War­rants can also now be obtained more eas­i­ly than ever, such as via the phone,73 and the Court has declined to ignore the war­rant require­ment when war­rants can be eas­i­ly obtained.74 Fur­ther, the nar­row approach does not pur­port to get rid of oth­er excep­tions to the war­rant require­ment, such as exi­gency. The crit­i­cal point is instead that the gov­ern­ment action will con­sti­tute a search and require fur­ther jus­ti­fi­ca­tion in order for it to be con­duct­ed with­out a warrant.

Since the nar­row approach focus­es on the nature of the device, it pos­es anoth­er dis­tinct prob­lem: courts will have to draw lines as to which devices con­sti­tute EMS­Ds, in addi­tion to eval­u­at­ing an officer’s lev­el of “cer­tain­ty” based on the infor­ma­tion that was relayed by the pri­vate par­ty and deter­min­ing what pri­va­cy inter­ests were already frus­trat­ed by the pri­vate par­ty. Yet, this task is not as wor­ry­ing as it seems at first blush. The Court has not­ed that the Fourth Amend­ment gen­er­al­ly requires a fact-spe­cif­ic inquiry in the first place.75 More­over, the key ques­tion is not what con­sti­tutes an EMSD, but whether the offi­cers had sub­stan­tial cer­tain­ty as to the con­tents of the device before per­form­ing their inves­ti­ga­tion, which can be informed by the type of device that holds the con­tents. If a rea­son­able offi­cer would know that the device in its ordi­nary usage has the poten­tial to store thou­sands of files, and if the pri­vate par­ty has not made a con­trary rep­re­sen­ta­tion, then the nar­row approach should apply.76


Courts must be care­ful “not to uncrit­i­cal­ly extend exist­ing prece­dents” when con­front­ed with new con­cerns brought by tech­nol­o­gy.77 Extend­ing the pri­vate search doc­trine over EMS­Ds beyond the con­fines of the nar­row approach would give an offi­cer the abil­i­ty to freely scour poten­tial­ly thou­sands of untouched, pri­vate files. The Court should not allow that to be the law. Indeed, the Fourth Amend­ment was enact­ed in response to gen­er­al war­rants and writs of assis­tance, as famous­ly argued against by James Otis in 1761, where­by gov­ern­ment offi­cials could rum­mage through a pri­vate party’s pos­ses­sions with­out the check of a detached mag­is­trate.78 The nar­row approach to the pri­vate search doc­trine both remains faith­ful to the Fourth Amend­ment and encour­ages offi­cers to seek warrants—two out­comes that are undoubt­ed­ly ben­e­fi­cial for all of society.

* William G. Walant is a J.D. Can­di­date (2022) at New York Uni­ver­si­ty School of Law. This Con­tri­bu­tion is a com­men­tary on a prob­lem pre­sent­ed in the Prince Evi­dence Moot Court Com­pe­ti­tion held in March 2021. The views expressed in this con­tri­bu­tion do not nec­es­sar­i­ly rep­re­sent the views of the author. Rather, this Con­tri­bu­tion is a dis­til­la­tion of one side of an argu­ment made by the author at the Competition.

1. U.S. Con­st. amend. IV, cl. 1.

2.Tay­lor v. City of Sag­i­naw, 922 F.3d 328, 332 (6th Cir. 2019).

3. Katz v. Unit­ed States, 389 U.S. 347, 360 (1967) (Har­lan, J., concurring).

4. Unit­ed States v. Jones, 565 U.S. 400, 404 (2012).

5. Whether the pri­vate search doc­trine is lim­it­ed to the Katz half of the def­i­n­i­tion of a “search” or extends to the Jones def­i­n­i­tion is beyond the scope of this Con­tri­bu­tion. See gen­er­al­ly Andrew MacK­ie-Mason, The Pri­vate Search Doc­trine After Jones, 126 Yale L.J. Forum 326 (2017).

6. Bur­deau v. McDow­ell, 256 U.S. 465, 475 (1921).

7. Coolidge v. New Hamp­shire, 403 U.S. 443, 489 (1971) (plu­ral­i­ty opinion).

8. Unit­ed States v. Jacob­sen, 466 U.S. 109, 119 (1984). See also id. at 117 (“The Fourth Amend­ment is impli­cat­ed only if the author­i­ties use infor­ma­tion with respect to which the expec­ta­tion of pri­va­cy has not already been frustrated.”).

9. See gen­er­al­ly id. at 109 (rul­ing direct­ly on the pri­vate search doc­trine); Wal­ter v. Unit­ed States, 447 U.S. 649, 649 (1980) (plu­ral­i­ty opin­ion) (same).

10. 573 U.S. 373 (2014).

11. Id. at 386 (not­ing, inter alia, that “[a] search of the infor­ma­tion on a cell phone bears lit­tle resem­blance to the type of brief phys­i­cal search con­sid­ered in [Unit­ed States v. Robin­son, 414 U.S. 218 (1973)].”).

12. See id. at 401.

13. See Alexan­dra Gios­ef­fi, Licht­en­berg­er, Sparks, and Wicks: The Future of the Pri­vate Search Doc­trine, 66 Emory L.J. 395, 424 (2017) (describ­ing the approach adopt­ed by the Fifth and Sev­enth Cir­cuits as giv­ing “gov­ern­ment offi­cials . . . broad author­i­ty to search devices more thor­ough­ly and view more files with­out fear of vio­lat­ing the own­ers’ Fourth Amend­ment rights”).

14. 275 F.3d 449 (5th Cir. 2001).

15. Id. at 453.

16. Id. at 453–54.

17. Id. at 463 (“The guide­line that emerges . . . is that the police exceed the scope of a pri­or pri­vate search when they exam­ine a closed con­tain­er that was not opened by the pri­vate searchers unless the police are already sub­stan­tial­ly cer­tain of what is inside that con­tain­er based on the state­ments of the pri­vate searchers, their repli­ca­tion of the pri­vate search, and their expertise.”).

18. Id. at 464.

19. 689 F.3d 832 (7th Cir. 2012).

20. Id. at 838.

21. Specif­i­cal­ly, in adopt­ing the Fifth Circuit’s rul­ing, the Sev­enth Cir­cuit high­light­ed the Fifth Circuit’s anal­o­gy between dig­i­tal media stor­age devices and con­tain­ers. Id. at 836–37.

22. Id. at 838 (empha­sis added).

23. See Gios­ef­fi, supra note 13, at 418.

24. Unit­ed States v. Wicks, 73 M.J. 93, 100 (C.A.A.F. 2014) (empha­sis added). The court in Wicks went on to deduce that, even assum­ing Run­yan was cor­rect in analo­giz­ing com­put­er disks to stor­age con­tain­ers, cell phones and lap­tops present unique chal­lenges that demand a dif­fer­ent pri­vate search doc­trine analy­sis. Id. at 102. See also Orin S. Kerr, Search­es and Seizures in A Dig­i­tal World, 119 Harv. L. Rev. 531, 548 (2005) (“Under this approach, a search of data stored on a hard dri­ve occurs when that data, or infor­ma­tion about that data, is exposed to human obser­va­tion. . . . Under this approach, . . . in the case of a search by a pri­vate actor, gov­ern­ment agents may view only the infor­ma­tion viewed by the pri­vate actor unless they first obtain a war­rant.”); Gios­ef­fi, supra note 13, at 415 (“The par­tic­u­lar­i­ty approach devel­oped inde­pen­dent­ly in dif­fer­ent juris­dic­tions, but the com­mon thread among appli­ca­tions remains the agree­ment that gov­ern­ment search­es of elec­tron­ic devices should be narrowly-tailored.”).

25. 786 F.3d 478 (6th Cir. 2015).

26. Id. at 480–81.

27. Id. at 487, 489. More­over, although Wicks only involved a cell phone and explic­it­ly stat­ed that cell phones and lap­tops present chal­lenges “well beyond com­put­er disks,” it was only assum­ing arguen­do that com­put­er disks were akin to con­tain­ers. 73 M.J. at 102.

28. 758 F. App’x 437 (6th Cir. 2018).

29. Id. at 439.

30. Id. at 442.

31. Id. at 453 (Bush, J., con­cur­ring in the judg­ment and con­cur­ring in part). Ulti­mate­ly, Judge Bush found that because “rea­son­able courts have disagreed—and rea­son­able offi­cers could be uncertain—about whether the best read­ing of Jacob­sen requires an ex ante or an ex post analy­sis, or some com­bi­na­tion of both,” the offi­cer was act­ing “objec­tive­ly rea­son­able.” Id.

32. 806 F.3d 1323 (11th Cir. 2015), over­ruled on oth­er grounds by Unit­ed States v. Ross, 963 F.3d 1056 (11th Cir. 2020) (en banc).

33. Id. at 1331–32.

34. Id. at 1336.

35. Id. (not­ing that there is no “safe har­bor for a gov­ern­men­tal search of mate­ri­als beyond the scope of a pri­vate search”).

36. See Unit­ed States v. Jacob­sen, 466 U.S. 109, 130 (1984) (White, J., con­cur­ring) (“The pri­vate search doc­trine thus has much in com­mon with the plain-view doc­trine, which is ‘ground­ed in the propo­si­tion that once police are law­ful­ly in a posi­tion to observe an item first-hand, its owner’s pri­vate inter­est in that item is lost.’” (quot­ing Illi­nois v. Andreas, 463 U.S. 765, 771 (1983))).

37. See Thomas K. Clan­cy, The Fourth Amend­ment Aspects of Com­put­er Search­es and Seizures: A Per­spec­tive and A Primer, 75 Miss. L.J. 193, 243 (2005) (“Under­ly­ing the pri­vate search doc­trine is the view that the pri­vate par­ty has already dis­cov­ered what is in the con­tain­er; in [Wal­ter]’s words, the pri­vate par­ty has elim­i­nat­ed the owner’s rea­son­able expec­ta­tion of pri­va­cy in the con­tents of the container.”).

38. Wal­ter v. Unit­ed States, 447 U.S. 649, 659, 659 n.13 (1980) (plu­ral­i­ty opinion).

39. See U.S. Con­st. amend. IV, cl. 2 (“No war­rants shall issue, but upon prob­a­ble cause . . . par­tic­u­lar­ly describ­ing the place to be searched, and the per­sons or things to be seized.”); Wal­ter, 447 U.S. at 657 (“If a prop­er­ly autho­rized offi­cial search is lim­it­ed by the par­tic­u­lar terms of its autho­riza­tion, at least the same kind of strict lim­i­ta­tion must be applied to any offi­cial use of a pri­vate party’s inva­sion of anoth­er person’s privacy.”).

40. See Jacob­sen, 466 U.S. at 115 (the government’s sub­se­quent search “must be test­ed by the degree to which they exceed­ed the scope of the pri­vate search”).

41. That is, as explained in this para­graph, the “vir­tu­al” or “sub­stan­tial” cer­tain­ty require­ment. See infra note 42 and accom­pa­ny­ing text.

42. Jacob­sen, 466 U.S. at 119. Indeed, “the crit­i­cal mea­sures of whether a gov­ern­men­tal search exceeds the scope of the pri­vate search that pre­ced­ed it are how much infor­ma­tion the gov­ern­ment stands to gain when it re-exam­ines the evi­dence and, relat­ed­ly, how cer­tain it is regard­ing what it will find.” Unit­ed States v. Licht­en­berg­er, 786 F.3d 478, 485–86 (6th Cir. 2015).

43. Jacob­sen, 466 U.S. at 123–24 (empha­sis added).

44. 462 U.S. 696 (1983).

45. Id. at 707. See also Wal­ter v. Unit­ed States, 447 U.S. 649, 657 (1980) (plu­ral­i­ty opin­ion) (find­ing it insuf­fi­cient that “[p]rior to the Gov­ern­ment screen­ing one could only draw infer­ences about what was on the films.”).

46. This focus on the nature and con­tents of EMS­Ds com­ports with Riley. In Riley, the Supreme Court empha­sized that smart phones present height­ened pri­va­cy con­cerns under the Fourth Amend­ment in large part because of their stor­age capac­i­ty and preva­lence in dai­ly life. See Riley v. Cal­i­for­nia, 573 U.S. 373, 394 (2014). While it is true that “an elec­tron­ic device does not change the fun­da­men­tals of [the Fourth Amend­ment] inquiry . . . under Riley, the nature of the elec­tron­ic device great­ly increas­es the poten­tial pri­va­cy inter­ests at stake, adding weight to one side of the scale while the oth­er remains the same.” Licht­en­berg­er, 786 F.3d at 488.

47. Each “byte” is a mea­sure of stor­age space, with each megabyte equal­ing one mil­lion bytes of infor­ma­tion. For instance, a typ­i­cal JPEG image is around 5 megabytes. Patrick Whiten­er, Flash Dri­ve Sizes: How to Find the Cor­rect Size for Your Needs, USB Mem­o­ry Direct: Blog (July 6, 2021),

48. See Flop­py Disk Capac­i­ty, Dig­it. Scrap­book­ing Stor­age, (last vis­it­ed Jan. 20, 2022); CD DVD Stor­age Media for Pre­serv­ing Your Dig­i­tal Mem­o­ries, Dig­it. Scrap­book­ing Stor­age, (last vis­it­ed Jan. 20, 2022); Whiten­er, supra note 47.

49. Unit­ed States v. Com­pre­hen­sive Drug Test­ing, Inc., 513 F.3d 1085, 1108 (9th Cir. 2008) (quo­ta­tion marks omit­ted), reh’g en banc, 579 F.3d 989 (2009), opin­ion revised and super­seded on oth­er grounds, 621 F.3d 1162 (2010); see also Unit­ed States v. Crist, 627 F. Supp. 2d 575, 585 (M.D. Penn. 2008) (“Com­put­ers are com­posed of many com­part­ments, among them a ‘hard dri­ve,’ which in turn is com­posed of many ‘plat­ters,’ or disks.”).

50. Unit­ed States v. Jacob­sen, 466 U.S. 109, 123–24 (1984).

51. Cf. Riley, 573 U.S. at 395 (dis­cussing the per­va­sive­ness of cell phones).

52. For exam­ple, the EMSD will like­ly con­tain fold­ers with per­son­al mes­sages or inti­mate photos.

53. Unit­ed States v. Run­yan, 275 F.3d 449, 464 (5th Cir. 2001).

54. See Wal­ter v. Unit­ed States, 447 U.S. 649, 657 (1980) (plu­ral­i­ty opin­ion). For exam­ple, the EMSD will like­ly con­tain many unre­lat­ed fold­ers, or it may con­tain pho­to albums doc­u­ment­ing dis­parate years in someone’s life.

55. See 573 U.S. at 380–81.

56. Id. at 393 (“[M]any [mod­ern cell phones] are in fact mini­com­put­ers . . . . One of the most notable dis­tin­guish­ing fea­tures of mod­ern cell phones is their immense stor­age capac­i­ty.”) (empha­sis added).

57. See supra notes 48, 52, and 54 and accom­pa­ny­ing text.

58. For exam­ple, a con­cerned pri­vate par­ty down­loads the con­tents of the defendant’s com­put­er onto a flash dri­ve. See, e.g., Unit­ed States v. Licht­en­berg­er, 786 F.3d 478, 490 n.6 (6th Cir. 2015).

59. See, e.g., Unit­ed States v. Robin­son, 414 U.S. 218, 224 (1973) (hold­ing that the search of a cig­a­rette pack sub­se­quent to an arrest—which already frus­trates an expec­ta­tion of privacy—comports with the Fourth Amend­ment); Cal­i­for­nia v. Car­ney, 471 U.S. 386, 391–92 (1985) (hold­ing that mobile homes are sub­ject to the “auto­mo­bile excep­tion” because they have dimin­ished rea­son­able expec­ta­tions of privacy).

60. Under the nar­row approach, the scope of the frus­trat­ed pri­va­cy inter­ests depends on what the pri­vate par­ty had actu­al­ly viewed. Still, the rea­son­able­ness of the officer’s search can be assessed by con­sid­er­ing what the pri­vate par­ty had relayed to the offi­cer. “The rea­son­able­ness of an offi­cial inva­sion of the citizen’s pri­va­cy must be appraised on the basis of the facts as they exist­ed at the time that inva­sion occurred.” Unit­ed States v. Jacob­sen, 466 U.S. 109, 115 (1984).

[61] Fur­ther, if an offi­cer instructs or coerces the pri­vate par­ty to go through each file, that inves­ti­ga­tion would like­ly be con­sid­ered a search under the Fourth Amend­ment: the pri­vate par­ty is act­ing under the direc­tion of the offi­cer, deem­ing them a gov­ern­ment agent. See Wal­ter v. Unit­ed States, 447 U.S. 649, 662 (1980) (Black­mun, J., dis­sent­ing) (“[T]he Fourth Amend­ment pro­scribes only gov­ern­men­tal action, and does not apply to a search or seizure, even an unrea­son­able one, effect­ed by a pri­vate indi­vid­ual not act­ing as an agent of the Gov­ern­ment or with the par­tic­i­pa­tion or knowl­edge of any gov­ern­men­tal offi­cial.”). The con­tours of what con­sti­tutes “act­ing as an agent” of the gov­ern­ment is beyond the scope of this Contribution.

62. Put suc­cinct­ly, even if a pri­vate par­ty rep­re­sents they have viewed every file con­tained in an EMSD, an offi­cer will still be risk­ing sup­pres­sion giv­en that an EMSD has a large stor­age capac­i­ty and a high chance of hold­ing pre­vi­ous­ly unviewed per­son­al or unre­lat­ed files. See supra notes 48, 52, and 54 and accom­pa­ny­ing text.

63. See Dylan Bon­figli, Get A War­rant: A Bright-Line Rule for Dig­i­tal Search­es Under the Pri­vate-Search Doc­trine, 90 S. Cal. L. Rev. 307, 329–30 (2017) (“Instead of try­ing to fit dig­i­tal search­es into the exist­ing pri­vate-search frame­work, . . . courts should adopt a rule like the one seen in Riley—a bright-line rule that exempts dig­i­tal search­es from the pri­vate-search exception.”).

64. Bri­an­na M. Espeland, Impli­ca­tions of the Pri­vate Search Doc­trine in A Dig­i­tal Age: Advo­cat­ing for Lim­i­ta­tions on War­rant­less Search­es Through Adop­tion of the Vir­tu­al File Approach, 53 Ida­ho L. Rev. 777, 833 (2017).

65. Such due dili­gence might include walk­ing through the EMSD’s con­tents with the pri­vate par­ty to ensure the party’s rep­re­sen­ta­tion was accurate.

66. In addi­tion to assum­ing the offi­cer is rea­son­able and that a rea­son­able offi­cer would pre­fer guar­an­teed admit­tance of evi­dence to the risk of sup­pres­sion, this cal­cu­la­tion assumes that the new infor­ma­tion an offi­cer comes upon would be entered in at tri­al and thus face sup­pres­sion. An offi­cer may instead decide to improp­er­ly intrude upon a pri­va­cy inter­est and nev­er risk sup­pres­sion because they do not intend to enter that evi­dence in at tri­al. Yet, this lim­i­ta­tion to suppression’s effi­ca­cy as a deter­rence mech­a­nism to war­rant­less search­es is inher­ent in the Supreme Court’s Fourth Amend­ment doc­trine and so is essen­tial­ly con­stant; there­fore, it should not detract from the con­clu­sion that the nar­row approach at least pro­vides a high­er incen­tive to obtain a war­rant rel­a­tive to the broad approach.

67. An officer’s “lack of cer­tain­ty” as to the con­tents of an EMSD should not be con­fused with an officer’s “lack of clar­i­ty” as to what con­sti­tutes per­mis­si­ble con­duct. The Supreme Court has pre­vi­ous­ly not­ed in a dif­fer­ent con­text that if an offi­cer can nev­er be sure if what they are doing is con­sti­tu­tion­al, the frame­work is imper­mis­si­ble. Kyl­lo v. Unit­ed States, 533 U.S. 27, 39 (2001). But it is not the case that the nar­row approach would mean offi­cers are nev­er clear if what they are doing is con­sti­tu­tion­al: whether an offi­cer believes they have suf­fi­cient cer­tain­ty to exam­ine the con­tents of an EMSD will be read­i­ly appar­ent (e.g., the pri­vate par­ty rep­re­sent­ed they viewed all of a flash drive’s files and walked the offi­cer through all of those files but no new con­tent emerged). Rather, the nar­row approach means that offi­cers under­stand they will almost nev­er have suf­fi­cient cer­tain­ty regard­ing the con­tents of an EMSD so as to make their con­duct constitutional.

68. Cama­ra v. Mun. Court of City and Cty. of S.F., 387 U.S. 523, 528 (1967) (“The basic pur­pose of this Amend­ment, as rec­og­nized in count­less deci­sions of [the Supreme] Court, is to safe­guard the pri­va­cy and secu­ri­ty of indi­vid­u­als against arbi­trary inva­sions by gov­ern­men­tal officials.”).

69. See John­son v. Unit­ed States, 333 U.S. 10, 17 (1948) (not­ing that absolv­ing the war­rant require­ment “would oblit­er­ate one of the most fun­da­men­tal dis­tinc­tions between our form of gov­ern­ment, where offi­cers are under the law, and the police-state where they are the law.”).

70. Katz v. Unit­ed States, 389 U.S. 347, 357 (1967) (Har­lan, J., con­cur­ring) (inter­nal quo­ta­tions and cita­tions omit­ted) (first alter­ation in original).

71. See Unit­ed States v. Run­yan, 275 F.3d 449, 463 (5th Cir. 2001) (call­ing its broad­er approach “sen­si­ble because it pre­serves the com­pet­ing objec­tives under­ly­ing the Fourth Amendment’s pro­tec­tions against war­rant­less police search­es,” which includes bal­anc­ing the government’s inter­ests); see also Rann v. Atchi­son, 689 F.3d 832, 837 (7th Cir. 2012) (same).

72. See Mincey v. Ari­zona, 437 U.S. 385, 393 (1978) (“[T]he mere fact that law enforce­ment may be made more effi­cient can nev­er by itself jus­ti­fy dis­re­gard of the Fourth Amend­ment. . . . The inves­ti­ga­tion of crime would always be sim­pli­fied if war­rants were unnec­es­sary. But the Fourth Amend­ment reflects the view of those who wrote the Bill of Rights that the pri­va­cy of a person’s home and prop­er­ty may not be total­ly sac­ri­ficed in the name of max­i­mum sim­plic­i­ty in enforce­ment of the crim­i­nal law.”).

73. Fed. R. Crim. P. 4.1(d)(3).

74. Cf. Mis­souri v. McNeely, 569 U.S. 141, 155 (2013) (“[T]echnological devel­op­ments that enable police offi­cers to secure war­rants more quick­ly, and do so with­out under­min­ing the neu­tral mag­is­trate judge’s essen­tial role as a check on police dis­cre­tion, are rel­e­vant to an assess­ment of exigency.”).

75. See, e.g., Gra­ham v. Con­nor, 490 U.S. 386, 396 (1989) (“Because ‘[t]he test of rea­son­able­ness under the Fourth Amend­ment is not capa­ble of pre­cise def­i­n­i­tion or mechan­i­cal appli­ca­tion,’ . . . its prop­er appli­ca­tion requires care­ful atten­tion to the facts and cir­cum­stances of each par­tic­u­lar case.” (quot­ing Bell v. Wolfish, 441 U.S. 520, 559 (1979))).

76. See Unit­ed States v. Jacob­sen, 466 U.S. 109, 115 (1984). While this Con­tri­bu­tion has set out to argue that all EMS­Ds should be sub­ject to the nar­row approach, the approach should at the very least apply to flash dri­ves, giv­en the sheer amount of data they can hold. The Fifth and Sev­enth Cir­cuits’ hold­ings regard­ing CDs, zip dri­ves, and flop­py disks, which have com­par­a­tive­ly less stor­age capac­i­ties, are then arguably con­sis­tent with this approach and might not need to be over­turned. See supra note 48.

77. Car­pen­ter v. Unit­ed States, 138 S. Ct. 2206, 2222 (2018).

78. See Riley v. Cal­i­for­nia, 573 U.S. 373, 403 (2014) (quot­ing Let­ter from John Adams to William Tudor (March 29, 1817), in 10 Works of John Adams 247–48 (Boston, Lit­tle Brown & Co. 1856)); see also Boyd v. Unit­ed States, 116 U.S. 616, 625 (1886).