Brown said when the Senate returns next month, he would introduce the Mobile Device Theft Deterrence Act, which would impose criminal penalties of up to five years for thieves who tamper with cellphone identifiers known as International Mobile Equipment Identity (IMEI) numbers.

Cellphone carriers started using IMEIs in an agreement with the Federal Communications Commission (FCC) to allow stolen cellphones to be deactivated, but some criminals are tampering with those unique identifiers in order to avoid detection.

Brown said his bill would provide exceptions for legal alterations made to repair or refurbish phones or to protect the privacy and security of the end user.