The Mr. Robot actor's dad, Thomas Slater, 80, who is also known by his stage name of Michael Hawkins, brought a lawsuit against his son in February (16) alleging Christian had defamed him in a 2015 interview by claiming he had "manic-depressive schizophrenia".

However, at a court hearing in Los Angeles on Monday (25Jul16), Judge Suzanne Bruguera ruled Christian's comments in the interview counted as protected speech under California's anti-SLAPP (Strategic Lawsuit Against Public Participation) law.

The law in question allows defendants in lawsuits which involve activities protected by the U.S. constitution, such as free speech, to get the case thrown out if they can show a lawsuit has little chance of success.

According to The Hollywood Reporter, in her ruling Judge Bruguera found that Christian's comments about his father's alleged mental illness were in the public interest and therefore protected speech.

"The Court finds that the foregoing discussion sufficiently establishes that the Defendant's (Christian) statements were in the public interest, considering his celebrity status, the dramatic content of this aspect of his family relationships, and the underlying issue of mental illness and its effect on the family," she wrote in the ruling dismissing the case.

Thomas' lawsuit, and a similar one filed against Christian's mother Mary Jo had claimed the pair had ruined his acting career with public claims he was mentally ill.

The lawsuit against Mary Jo has not yet been dismissed, although her lawyer told the judge that she also intends to pursue the dismissal of the case.

Thomas, whose last major acting role was in the 1988 Robert De Niro comedy Midnight Run, indicated he intended to appeal against the dismissal of the lawsuit against his son.

"I will be appealing this," he told the New York Daily News after the hearing. "Christian is not going to get away with this."

Mr. Robot, in which Christian plays the title character, has won acclaim for both its portrayal of technology and the nature of mental illness. Its second season debuted on U.S. TV earlier this month (Jul16).