Marquette University Law School professor Dan Blinka said no matter how it's described, the resolution calls for what amounts to an arrest that would have to be justified under the law. If it's found unconstitutional, any action taken by the senators after they were forced to return could be invalidated, Blinka said.

Howard Schweber, an associate political science and law professor at the University of Wisconsin-Madison, said Senate Republicans can properly order police to enforce their rules, as long as they don't try to impose criminal sanctions on the Democrats.

"The resources of the executive branch can be called upon by the Legislature to enforce its rules," Schweber said. "I would suspect the Republicans have this one right. They probably are able to use police as a mechanism to enforce the rules of the Senate even though they would not be able to make failure to appear a crime."

A memo provided by private attorney Jim Troupis, who was hired by the Senate Republicans and often works with the GOP, said the state constitution gives them authority to act to compel attendance under its rules.