The Fulton County Board of Commissioners on Wednesday approved a 17 percent property tax increase, defying a cap imposed last year by state legislators and setting up a possible confrontation in court.

By a 4-3 vote, commissioners approved a tax hike that will generate about $50 million for libraries, courts, social services and other programs. It’s the first time Fulton has raised its countywide tax rate since 1991.

“It means the continuation of services for Grady Hospital, for seniors, for youths,” said Chairman John Eaves, who supported the measure.

But critics say Fulton should be able to balance its budget without raising taxes.

“I don’t think we’ve made enough structural changes to our organization,” said Commissioner Liz Hausmann, who voted against the tax increase.

Last year, the General Assembly approved a law prohibiting Fulton from raising its tax rate until 2015. The law also requires a supermajority of commissioners to raise taxes beginning next year.

But Fulton commissioners say the law is an illegal intrusion into local affairs and voted to repeal it last year, citing their home rule powers under the state constitution. Wednesday’s vote may spark a court battle over whether the county violated state law.

The tax increase will cost the owner of a $275,000 home an extra $140 a year. But with property values rising fast in some areas, some taxpayers could be in for a shock. If a house worth that amount last year increases 10 percent in value, the tax hike would cost an extra $270 a year.

At a public hearing before the vote, some residents urged commissioners to reject the tax hike and reduce costs instead.

“Challenge your staff to go find the opportunities, to find the waste that is out there,” said John Terry of Sandy Springs.

Commissioners heard similar testimony over the course of several recent public hearings on the tax hike. But they also heard from residents who want to protect arts programs, senior centers and other services.

“The county has kept its millage rate low,” said Greg Fann, executive director of the county employees union. “But we’ve got important things that need to be done.”

Wednesday, commissioners also approved an administrative reorganization that could save Fulton as much as $5 million in 2015. County Manager Dwight Ferrell said reshuffling departments would simplify Fulton’s administrative structure and reduce expenses in the personnel, finance, information technology and purchasing departments.

Cobb, DeKalb, Gwinnett and other metro counties have raised property tax rates in recent years to offset declining property values and boost revenue. Fulton County, which hasn’t raised taxes in 23 years, instead relied on reserve funds to balance its budget.

But reserves are dwindling, and in January commissioners cut spending on Grady Memorial Hospital, libraries and other services. The budget approved in January assumed commissioners would raise the property tax rate.

Commissioners voted on the tax increase without discussing it. Though some commissioners asked to speak, Eaves rejected their request and called for a vote.

That angered Commissioner Robb Pitts, who voted against the tax increase.

“It was not professional. It was discourteous,” Pitts said. “I think the public had a right to know how individual commissioners think and feel about that budget.”

“We’ve been debating this for the last month and a half,” Eaves said.