united-states rules-of-evidence
Is evidence obtained under false pretences admissable in a criminal trial?
<p>Is evidence obtained under false pretences admissable in a criminal trial?</p>

<p>For example, imagine a policeman impersonates a computer technician to gain admittance to the suspect's home in order to "fix" the suspect's computer and in the course of doing this sees incriminating data.</p>

<p>Can the policeman testify in court against the suspect as to what he saw on the computer?</p>

<p>Yes and no. Using deception to get someone to open the door so that you can execute a warrant is okay (United States v. Contreras-Ceballos, 999 F.2d 432). Leading a criminal to believe that you are a crime-customer (e.g. for purposes of a drug sale) and not a police officer is okay (Lewis v. United States, 385 U.S. 206), but must be limited to the purposes contemplated by the suspect and cannot turn into a general search. Lying about whether you have a warrant is not okay (Bumper v. North  Carolina, 391 U.S. 543, Hadley v. Williams, 368 F.3d 747), nor is it okay to lie about the scope of a warrant (United  States  v.  Dichiarinte, 445 F.2d 126). Misrepresenting the true purpose of entry, even when the person is identified as a government agent, negates consent (US v. Bosse, 898 F. 2d 113; United States v. Phillips, 497 F.2d 1131; United States v. Tweel, 550 F.2d 297). However, there is no requirement to be fully forthright (US v. Briley, 726 F.2d 1301) so you can gain entry saying that you "have a matter to discuss with X" even when the intent is to arrest X.</p>

<p>In a case similar to what you describe, <a href="https://casetext.com/case/united-states-v-phua-2" rel="noreferrer">United States v. Wei Seng Phua, 100 F.Supp.3d 1040</a>, FBI agents disrupted internet access and then posed as repairmen to gain access to the computer. Their efforts were wasted, as fruits of the poisonous tree.</p>
