MINNEAPOLIS — A Minnesota blogger who has written about two Lakeville sisters who went missing claims his constitutional rights are being violated after he was served with a restraining order.

The girls’ mother, Sandra Grazzini-Rucki, got the restraining order against Michael Brodkorb because she claimed he was harassing her and she feared her safety due to “slanderous misinformation” that she said damaged her reputation.

Brodkorb, who writes about the case for his Missing in Minnesota blog, calls his work journalism and said the restraining order violates his First Amendment rights and ability to cover Grazzini-Rucki’s sentencing on Wednesday. He said nearly all of Grazzini-Rucki’s claims against him are false, including a claim that he followed her in his car.

Grazzini-Rucki’s attorney said Brodkorb went too far. Attorney Michelle MacDonald said she was with her client when Brodkorb followed them and they had to take evasive action to lose him.

“It’s not appropriate,” MacDonald said, adding that she mailed Brodkorb a document about reporters’ ethics. “I’m all for First Amendment rights, but there are lines that can’t be crossed.”

“The chilling effect is that if someone doesn’t like coverage, they could go to a courthouse and file what I believe to be a fraudulent document with fictitious information to game the system,” Brodkorb said.

Jane Kirtley, a University of Minnesota journalism professor, said a restraining order against a journalist is unusual. She said some of what Grazzini-Rucki describes falls into the category of persistent journalism, but journalists are not allowed to break the law to report a story. She said the judge might have to determine whether Brodkorb did just that.

Grazzini-Rucki was convicted in July of felony deprivation of parental rights for hiding her daughters for more than two years from their father. She faces a year in jail under sentencing guidelines, but would get credit for time served.