I'm guessing this ruling is about taking the suspects actual finger and placing it on the scanner.
This is different from building a fake finger based on fingerprints and using it to unlock your device.
Consider the password case, you can't be compelled to give your password, but the government is allowed to throw all of their hacking prowess against your device to crack that password. They can even ask you about the name of your first pet to get through security questions. Though they can't compel you to answer truly regarding the name of your first pet.
Consider the password case, you can't be compelled to give your password, but the government is allowed to throw all of their hacking prowess against your device to crack that password. They can even ask you about the name of your first pet to get through security questions. Though they can't compel you to answer truly regarding the name of your first pet.