When the police have a search warrant, if you were doing something illegal with the cell phone, or if the cell phone contains evidence.
The U.S. Constitution's Fourth Amendment protects people against unreasonable searches and seizures. Traditionally, police searches consisted of searching one's home, car, or pockets for weapons and drugs. In the last twenty years, police often seized one's personal computers. And now with the ubiquity of mobile technology, police are frequently seizing one's cell phones.
There are three main circumstances under which law enforcement may seize you cell phones:
- The police have secured a valid search warrant signed by a judge that specifically authorizes the police to take the cell phone. But note that it may be possible for you to later contest the validity of the search warrant by arguing that it was improperly obtained or was overbroad.
- You were using the cell phone for an illegal purpose. Examples including using it to film child pornography or stealing someone's identity.
- The police have reason to believe your cell phone contains evidence. For instance if the police witnessed you selling drugs, the police would presume your cell phone contains communications between yourself and the drug buyer.
When cops seize cell phones, they have a duty not to erase or change any of the data on the cell phone. Read more on Nevada search and seizure laws.