Law enforcement agencies quickly latched on to the electronic trail of evidence. Crimes are easier to prove with a smoking gun email or text, or an incriminating photo posted to Facebook. Prosecutors often tack on wire fraud charges for extra leverage if the suspects used the internet or smartphones in furtherance of a crime.

But two U.S. appeals courts have reined in the power of police and prosecutors to use cellphone and social media accounts to fish for incriminating evidence. Search warrants for electronic mediums must still be specific and limited in scope, the same as physical searches of a citizen’s home or business.

Can police seize your cell phone?

In a 2-1 decision in August, the U.S. Court of Appeals for the District of Columbia threw out a firearm conviction that stemmed from a search warrant. The warrant, which sought any cellphones or electronic devices, led to the discovery of a gun, which led to prosecution and conviction for unlawful possession of a firearm. Two judges said the warrant was overly broad – police had no actual knowledge that the man owned a cellphone or reasonable suspicion they would find incriminating evidence on his phone. The dissenting judge said that discovery of the gun was incidental to good faith execution of the warrant.

Although the case, United States v. Griffin, did not hinge on any evidence found on the suspect’s cellphone, it raised a key issue. The question is whether police can assume that a citizen has a cellphone, and use that assumption to get a warrant to enter a home to search and seize property. It would give police broad powers beyond the typical scope of search warrants.

Can the government demand access to your Facebook information?

Also in August, the U.S. Circuit Court of Appeals for the 11th Circuit suggested limits on prosecutors seeking carte blanche access to suspects’ social media accounts. The case, United States v. Blake, involved search warrants served on Microsoft and Facebook in relation to the defendants’ email and Facebook accounts.

The 11th Circuit confirmed the validity of the Microsoft warrants, which required Microsoft to turn over only select emails that related to the alleged crimes. But the court took the prosecution to task for the Facebook warrants, which essentially demanded that Facebook turn over everything – private messages, uploaded photos, contact lists, search history, online purchases, etc. — so investigators could sift through it for evidence.

One circuit judge wrote: “The Facebook warrants are another matter. They required disclosure to the government of virtually every kind of data that could be found in a social media account. And unnecessarily so. … The warrants could have limited the request to messages sent to or from persons suspected at that time of being prostitutes or customers.”

Search warrants are not a catch-all

Anything posted on a public Facebook wall can be used by law enforcement. Emails and texts which are voluntarily turned over by senders or recipients are fair game, as well as messages specifically mentioned in a warrant.

But it’s another matter for the prosecution to seize your cellphone or your computer, or to subpoena your private Facebook or Instagram messages, because there might be evidence. Criminal charges that rely on unlawful search and seizure are a violation of the Fourth Amendment. Search warrants must be specific, necessary and as limited as possible.