INDIANAPOLIS — Part of a new Indiana law requiring teachers to renew requests every year for automatic paycheck deduction of union dues has been temporarily blocked by a federal judge.

U.S. District Judge Sarah Evans Barker said in her ruling Wednesday that the law violated educators’ free speech rights and that it “substantially impairs” existing contracts between school corporations and their teachers unions that allow for dues to be withdrawn from teachers’ paychecks.

Barker added that Republican Attorney General Todd Rokita did not adequately justify the new annual three-step process for the collection of teachers union dues, including a requirement that school districts send an email to all employees who have union dues deductions with a boldface message in 14-point type that they have the right to not join the union and may stop their paycheck deduction at any time.

The preliminary injunction prevents the state from enforcing the law, which took effect Thursday, to terminate any existing dues deduction withholding agreements until after the final pay period of the 2020-21 school year.

It also blocks the state from enforcing the law on any new agreements until the judge issues a final ruling.

Three Indiana teachers unions filed a federal lawsuit in June seeking to block the new requirement. They contend the law unfairly targets teachers and makes it harder for their unions to collect dues.