Image copyright Thinkstock Image caption A Canadian judge rules the prosecution had failed to prove the accused knew his behaviour was criminal

A Canadian man was found not guilty of rape because he believed he could have sex with his wife whenever he wanted.

Ontario Superior Court Justice Robert Smith ruled the prosecution failed to prove the accused man knew his behaviour was criminal.

The judge did not dispute that non-consensual sex had taken place multiple times, the Ottawa Citizen reported.

The man, from Gaza, was part of an arranged marriage with his wife, a Palestinian who grew up in Kuwait.

"Marriage is not a shield for sexual assault," Judge Smith wrote in his decision, according to the newspaper.

"However, the issue in this trial is whether, considering the whole of the evidence, the Crown has proven the allegations beyond a reasonable doubt."

The name of the accused and the complainant are being withheld due to a publication ban.

The judge found the prosecution did not prove beyond reasonable doubt that the man had criminal intent, known as "mens rea" in the law.

Both the man and the wife testified that they thought a husband was legally entitled to have sex with his wife whenever he wanted.

The wife said she had sex many times with her husband when she did not explicitly give her consent.

But when they separated in January 2013, the woman learned that she she had the right to refuse sex with her husband. She told police about an alleged 2002 incident, which eventually led to charges.

She alleged that he had pulled her onto the couch, pulled down her pants and had sex with her despite pleading with him to stop at least three times.

Her husband told the court he could not have had sex with her at the time because he had just received a hair transplant and he was following his doctor's orders to avoid intercourse

The judge said he found her to be a credible witness and rejected her husband's account, but said he could not find the man guilty of a crime.

Advocates against sexual violence were disappointed by the ruling.

Carrolyn Johnston, acting executive director of the Ottawa Coalition to End Violence Against Women, said the ruling reflects myths about sexual assault in our society.

"Any sexual contact without explicit and ongoing consent is sexual assault - regardless of the relationship," Ms Johnston told the BBC.

"He may have believed that he had a right to have sex with her as her husband, but Canadian sexual assault law is clear and was amended to include sexual assault against a spouse in 1983."