Wisconsin has comprehensive laws about how police are supposed to respond to domestic violence cases.
But an investigation by the Milwaukee Journal Sentinel found no one has authority to ensure police departments are responding as they should.
State statutes say local police must arrest domestic violence suspects, even if a victim doesn't cooperate.
The Brown Deer Police Department was criticized after officers didn't arrest Radcliffe Haughton, who killed his wife and two other women at a Brookfield spa last month.
Police Chief Steven Rinzel has defended the way his department handled an earlier incident involving Haughton, saying his wife didn't cooperate.
State leaders said they'll examine the issue. Gov. Scott Walker and a bipartisan group of legislators said more needs to be done to protect victims.