Biometrics might be cool and convenient, but the technology could potentially undermine your legal rights under the Fifth Amendment, which prohibits the government from compelling a witness to testify against herself.

A court or police officer could legally compel you to press your finger onto your smartphone to unlock it, but if your phone is locked with a passcode, no one can legally compel you to open it, says William J. Cook, an attorney and partner at law firm Reed Smith in Chicago, who specializes in information technology, privacy, and data security. Cook explains that the difference between a password and a biometric identifier is great under the law--you have a right not to reveal the contents of your mind, which includes things like a password, but your fingerprints are a part of who you are and you expose them to the public every day. This is why when a person gets arrested, he or she must consent to fingerprinted while retaining the right to remain silent. Thoughts are protected, biometric identifiers (fingerprints, face, hair) are not.

Ever since Apple introduced Touch ID in 2013, privacy law experts have been sounding the alarm about the way biometrics can whittle away at your right against self-incrimination.

"The Fifth Amendment protects individuals against saying anything, testimony or statements, that could incriminate them," says Paul Bond, who is also a partner at Reed Smith. "While it protects information, it does not shield physical things in the world available for production. Making the key to your information a physical key or biometric identifier is putting it in the realm of police power to produce."

The unlocking of smartphones and computers has become a legal niche, but this niche will soon grow to become a big part of many cases, Cook says. The FBI uses search warrants based on probable cause (the Fourth Amendment) to compel companies like Apple to unlock the phones belonging to alleged criminals to find evidence of crimes, but authorities are also gaining access to devices that use biometric identification systems, like Apple's Touch ID, by obtaining search warrants to force people to press a finger onto a mobile phone, Cook says.

Recently in Los Angeles, a federal judge signed a warrant to allow the FBI to force a 29-year-old woman to press her finger on an iPhone cops had seized from her boyfriend's home, an alleged gang member, the Los Angeles Times reported last week. This marked the first time a suspect had been forced to unlock an iPhone via Touch ID in a federal case.

More criminal investigations will involve accessing personal devices like smartphones, and biometric authentication technology is spreading to more devices. As even more employees download work-related information and data onto their personal phones, these three factors are conspiring to make company data a potential casualty of biometric technology's legal protection problem, Bond says.