A US Magistrate has rejected arguments Camille Cosby should be protected from testifying against her 78-year-old husband.

Lawyers for Ms Cosby said the 71-year-old should be excused from an upcoming deposition, citing the Massachusetts marital disqualification law.

The decision came as unnamed sources reportedly claimed she was aware of the comedian’s alleged infidelities.

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According to court documents, lawyers said the subpoena had placed “undue burden” on Mrs Cosby, the entertainer’s wife of more than 50 years.

They also argued “the value of any potentially admissible information is outweighed by the public interest in protecting marital communications”.

In Massachusetts, marital disqualification law prevents spouses from testifying on private conversations with their partner during their marriage, but certain criteria must be fulfilled for this to apply.

Presiding magistrate, Judge David Hennessy, rejected Ms Cosby’s argument for exemption.

“I find no merit in Mrs Cosby’s arguments,” the judge said in the order, “and accordingly deny her motion in its entirety”.

Unnamed family insiders claimed Ms Cosby was aware of her husband’s indiscretions, and had asked him to be discreet and not to shame her.

“But she has been thoroughly humiliated and, believe me, her anger isn’t directed at the women,” the unidentified source told The New York Post.

“Bill has humiliated her, and the affairs he’s had have gotten out of hand and this [criminal charge] is him reaping what he’s sown.”

They also claimed she was fighting the deposition “because it’s so humiliating” and was still married to the 78-year-old to avoid facing court.

“She knows that you can’t force a wife to testify against her husband and she doesn’t want any part of this at all,” the source said.

The entertainer was charged with sexual assault last week, after several women claimed they were “drugged and/or sexually assaulted”, court documents showed.

Earlier in December, Cosby launched a defamation countersuit against the women.

If convicted, Cosby faces up to 10 years in jail and a $25,000 fine. He was not expected back in court till mid-January.

Camille Cosby was scheduled to face court on Wednesday.