MADISON, Wis. — Wisconsin's polarizing union rights law will take effect thanks to a sharply divided ruling by the state Supreme Court that determined a judge overstepped her authority when she voided the governor's plan to strip most public workers of their collective bargaining rights.

The ruling Tuesday evening was a major victory for Republican Gov. Scott Walker, who said the law was needed to help address the state's $3.6 billion budget shortfall. His proposal — which drew tens of thousands of demonstrators to the state Capitol — thrust Wisconsin to the forefront of a national debate over labor rights.

In a 4-3 decision that included a blistering dissent, the Supreme Court ruled that Dane County Circuit Judge Maryann Sumi overstepped when she declared the law void last month. Sumi sided with a lawsuit that claimed Republicans didn't provide proper public notice of a meeting that helped get the original legislation approved after Democratic senators fled the state to prevent a vote.

Walker claimed that the law, which also requires public employees to pay more for their health care and pensions, would give local governments enough flexibility on labor costs to deal with deep cuts to state aid. Democrats saw it as an attack on public employee unions, which usually back their party's candidates.

“The Supreme Court's ruling provides our state the opportunity to move forward together and focus on getting Wisconsin working again,” Walker said in a one-sentence statement Tuesday.

Union leaders blasted the court's decision. Phil Neuenfeldt, president of the Wisconsin State AFL-CIO, called it “an affront to our democracy.”

An avalanche of lawsuits is expected, because legal challenges couldn't be brought until the law took effect.

In vacating Sumi's ruling, the Supreme Court ruled the judge had “usurped the legislative power which the Wisconsin Constitution grants exclusively to the legislature.” The court also rejected arguments that Republicans violated Wisconsin's open meetings law.

“The doors of the Senate and Assembly were kept open to the press and members of the public ... access was not denied,” according to the majority opinion.

In a fiery dissent, Supreme Court Chief Justice Shirley Abrahamson wrote that justices hastily reached the decision and the majority “set forth their own version of facts without evidence. They should not engage in this disinformation.”