The Chicago Police Department has tightened its policy on Taser use, rewriting the rules to discourage officers from shocking people who are running away or otherwise vulnerable to injury, reports the Chicago Tribune.

The change drew little public notice when the department enacted new use-of-force policies in October.

The revised order was issued a month and a half after a Chicago Tribune investigation detailing the department's reliance on the weapon pointed out that the rule changes the department had announced did not specifically ban shocking people who simply run away and pose no serious threat.

Facing a controversy sparked by officers' use of force, Superintendent Eddie Johnson oversaw a sweeping overhaul of the department's policies and introduced the new rules in May.

But five months after the new rules were unveiled, the department issued a Taser policy containing a lengthy revision. The order now includes a section that advises officers not to shock people who run away, are intoxicated, or could fall and suffer a head injury, among other things. The new language stops short of firmly banning Taser uses under those circumstances but says that "when practicable, department members should avoid" those uses.

The new policies face a challenge from the city’s largest police union, which filed a complaint with the Illinois Labor Relations Board arguing that the department violated the union’s collective bargaining rights by implementing new rules without negotiating. That challenge is pending.

Martin Preib, spokesman for the Chicago Fraternal Order of Police, said that the additional Taser restrictions are not reasonable and the policies should have been subject to bargaining.