In a victory for Gov. Bobby Jindal, the Louisiana Supreme Court on Wednesday upheld a hotly debated state law that makes it harder for public school teachers to earn and retain a form of job protection called tenure.

The ruling, for the second time, reversed a decision by state District Judge Michael Caldwell, of the 19th Judicial District Court in Baton Rouge.

Caldwell concluded that the overhaul was illegally approved by the Louisiana Legislature because it jammed too many subjects into a single bill.

The court disagreed, and handed the governor a big legal win on one of the most contentious issues of his 2012 public schools overhaul.

“This is good news,” Jindal said in a prepared statement. “Act 1 was created to help ensure we have a great teacher in every classroom, and we’re pleased that it will continue improving Louisiana’s schools for children and families across our state.”

The 24-page opinion was written by Justice Jeffrey P. Victory, of Shreveport. No justice filed a dissent to the opinion.

The key feature of the law makes it harder for public school teachers to earn and retain tenure, which backers said was badly needed because teachers routinely landed satisfactory ratings with only cursory reviews of their job performance.

The measure was heatedly opposed by teacher unions and other public school groups, including the Louisiana Federation of Teachers, which filed the lawsuit.

“Obviously the Louisiana Federation of Teachers is disappointed by the high court’s decision,” the group said in a prepared statement issued late Wednesday afternoon.

Caldwell ruled two times, including in January, that the tenure law was unconstitutional because he said it included multiple topics in a single bill.

But the state’s top court ruled that all of the subjects included in the law dealt with education and that, as such, the topics make up a “natural connection and are incidental and germane to that one object.

“Upon review, we find that Act 1 does not violate the single object requirement of the Louisiana Constitution,” according to the opinion.

The same court in June 2013 vacated Caldwell’s initial ruling that struck down the same law, with instructions that the judge take another look at the topic in light of a related ruling by the Supreme Court.

Caldwell stuck with his first ruling.

“I am still of the opinion that the act violates the single object requirement and is unconstitutional in its entirety,” he said from the bench in January.

Aside from the tougher tenure rules, the law requires performance objectives for local superintendents, redefines the role of local school boards, bans the exclusive use of seniority in layoff decisions and allows local officials to revamp salary schedules.

State Superintendent of Education John White, who was a key ally of Jindal when the tenure law won approval, praised Wednesday’s ruling by the Louisiana Supreme Court.

“Act 1 gives principals and superintendents freedom from politics to do the right thing for children,” White said in a prepared statement.

He said students in Louisiana are as smart as any and “deserve an education system in which adults make decisions based on merit and high expectations.”

The state has about 50,000 public school teachers, and the tenure law is part of an overhaul that radically changed their job reviews.

Under the new rules, teachers face annual evaluations instead of job checks once every three years.

Aside from being harder to earn tenure, teachers who already have the job protection can lose it and even be fired if they are repeatedly rated as ineffective in the classroom.

Backers said the changes will improve student achievement by ensuring quality teachers in every classroom.

Critics say that requiring new teachers to win top ratings for multiple years — part of the new mandate — is a near impossible task.

Even two years after approval of the tenure law, and four years since the Legislature passed a related measure, the issue continues to spark heated debates.

A state panel is considering ways to tweak teacher job checks but even those ideas generate still more arguments.

Follow Will Sentell on Twitter, @WillSentell. For more coverage of government and politics, follow our Politics Blog at http://blogs.theadvocate.com/politicsblog.