WASHINGTON (AP) - The head of the Internal Revenue Service says agents investigating crimes won't continue using cellphone-tracking technology without seeking a warrant.

WASHINGTON (AP) The head of the Internal Revenue Service says agents investigating crimes won't continue using cellphone-tracking technology without seeking a warrant.

Commissioner John Koskinen wrote about the new policy in a letter sent Nov. 25 to Democratic Sen. Ron Wyden of Oregon. Koskinen said his agency was drafting a policy to follow the Justice Department's rules, which require a warrant except in emergencies.

The IRS has used its cellphone-tracking technology to locate 37 cellular devices as part of 11 federal investigations since 2011.

Wyden and Republican Rep. Jason Chaffetz of Utah have introduced a bill requiring a warrant for government tracking of electronic data.

One such tracking device is known as a Stingray. It's the size of a suitcase and tricks cellphones into electronically identifying themselves, then transmits data to police.