After two mistrials, an adult film producer has been sentenced to four years in US prison after he was convicted of violating federal obscenity laws by selling movies depicting bestiality and other extreme fetishes.

US District Judge George King gave Ira Isaacs the sentence and ordered him to pay more than US$10,000 in fines and court costs.

In April, a jury found Isaacs, 62, guilty of five counts, including mailing obscene matter. He faced anywhere from probation to a 20-year prison sentence.

The jury had to watch the four Isaacs films named in the charges in their entirety. Most showed fetishes involving faeces. Jurors deliberated for just two hours before delivering the verdict.

Isaacs' attorney Roger Jon Diamond told City News Service that they planned to appeal.

The sentencing caps a sometimes bizarre, five-year, three-trial legal saga. A 2008 trial was halted after the Los Angeles Times reported Alex Kozinski, chief judge of the 9th US Circuit Court of Appeals, had sexually explicit material on a personal website.

Kozinski, who presided over the trial, recused himself and was admonished by a special committee of his colleagues.

Isaacs was indicted as part of an effort by a Bush administration task force to crack down on smut in the United States.

At issue at the trial was whether the videos sold by Isaacs were obscene. The test hinged on a 1973 US Supreme Court ruling that held that a work is not legally obscene if it has "literary, artistic, political or scientific value."

Jurors also were asked to decide whether the videos violated standards of what is acceptable to the community at large.

Isaacs defended himself as a champion of free speech, but he found very little support in the more mainstream porn community.

- AAP