DETROIT — A judge ruled today that Mayor Kwame Kilpatrick didn’t violate conditions of his bail in an assault case by visiting his sister, who is listed as a witness in the case.

Judge Ronald Giles rejected a prosecution move, agreeing with the mayor’s attorneys that a no-contact order didn’t include Ayanna Kilpatrick. The mayor had spent time with his sister during the weekend.

“I don’t see the issue,” the judge said. “I really don’t. There isn’t an issue.”

Last week, Judge Giles had sent the mayor to jail overnight in a separate perjury case after learning he had traveled to Windsor, Ontario, in July without notifying authorities, a condition of his release on bail.

Mr. Kilpatrick was released Friday.

That same day, the mayor was charged with assaulting two investigators who were trying to deliver a subpoena at his sister’s house in July in the perjury case.

The state attorney general’s office said in a court filing that the mayor had been ordered to have no contact with witnesses in the assault case.

Prosecutors said Mr. Kilpatrick violated that condition because he and Ayanna Kilpatrick were together Saturday at the home of their mother, Rep. Carolyn Cheeks Kilpatrick, a Democrat of Michigan.

“Clearly, a court can prevent contact with relatives,” Doug Baker, of the Michigan attorney general’s office, which is handling the assault case against Mr. Kilpatrick, said. “That happens all the time.”

A defense lawyer, James Thomas, said Magistrate Renee McDuffee clarified Friday that Mr. Kilpatrick could have contact with his sister. Thomas argued the mayor should be able to have the support of his family.

“I think this is a tempest in a teapot,” Mr. Thomas said.

Judge Giles said today the no-contact order was for the two investigators involved in the altercation.

However, the judge ordered the mayor not to contact another woman on the prosecution’s list of potential witnesses. Mr. Baker told the court that the woman had expressed fear about cooperating with prosecutors.