The judge pointed out to Mr. Weinstein his lawyers would face an ethical problem if the actress were called to testify against him.

Mr. Weinstein, 66, faces five charges in Manhattan, including rape and two counts of predatory sexual assault, which carries a maximum sentence of life in prison. The charges are related to one woman who accused Mr. Weinstein of raping her in a Midtown hotel and another who said he performed oral sex on her against her will in his apartment.

He has denied the allegations and has said the relationships were consensual.

Ms. McGowan has been a vocal critic of the movie producer and was one of the first women to come forward and accuse him of sexual misconduct. She said Mr. Weinstein assaulted her during a film festival in Utah in 1997, but charges were never filed. It is possible she could be called to testify about her experience to establish a pattern of behavior.

Ms. McGowan has criticized the lawyers for taking the Hollywood producer’s case, calling it an “egregious conflict of interest.”

Mr. Baez and Mr. Sullivan represented Ms. McGowan in November 2017 when she faced drug possession charges in Virginia. She had accused Mr. Weinstein of having a hand in her arrest, saying, without evidence, that he had the drugs planted in her wallet.