Increasingly, law enforcement relies on “smoking gun” evidence from smartphones. Phones can either be a conduit for committing crimes or leave a trail of electronic bread crumbs for police.

The only barrier is accessing the content of the phones. A recent federal court ruling put new limits on how far police, prosecutors and judges can go in forcing citizens to unlock their phones.

Federal judge says all passcodes are protected

The Fourth Amendment protects you from unlawful search and seizure. The Fifth Amendment protects you from self-incrimination. Can police confiscate your cellphone? If so, are you obligated to give them password?

In general, under previous federal court and U.S. Supreme Court rulings:

• Police can view the contents of your phone if it is voluntarily offered or discovered in a lawful search. (Emphasis lawful.)
• Police can confiscate phones with a search warrant. But the warrant must be specific. They cannot issue a blanket demand to see any and all phones that a suspect may have.
• Alphanumeric passcodes are protected. Law enforcement cannot force you to divulge your secret password, even with a warrant.
• Biometric passcodes are fair game. With a warrant, police can make you open your phone if it is protected by a fingerprint, voice recognition, face recognition or retina scan.

But a federal judge in California recently ruled that all passcodes are protected under the Fifth Amendment. In denying a search warrant, Judge Kandis Westmore of U.S. District Court for the Northern District of California said: “If a person cannot be compelled to provide a (alphanumeric) passcode because it is a testimonial communication, a person cannot be compelled to provide one’s finger, thumb, iris, face, or other biometric feature to unlock that same device.”

Your phone is not as private as you think

With rare exceptions, law enforcement cannot eavesdrop on your phone conversations or intercept electronic communications. But they can access that information at the other end. Social media is fair game. Anything you post on Instagram, Snapchat or Facebook from your phone can be used against you. With limitations, law enforcement can subpoena private messages or postings to private groups.

You also have no control over emails, texts or instant messages once they are sent to a third party. If that person willingly shares it with law enforcement, or cuts a deal, it can be used against you.

The California federal court ruling on biometric logins could be contradicted by other federal courts or overturned by a higher court. Or it may survive legal challenges and become the law of the land. Meanwhile, it’s just good sense – aside from any criminal implications – to protect your phone with a strong keypad password and to live your life under the assumption that anything sent from your phone can come back on you.