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WASHINGTON (AP) — In retrospect, Gary Peel's first mistake on the road to his conviction on child pornography charges was the affair he began in 1974 with his sister-in-law. She was 16 at the time.

It probably also was not a good idea to take nude pictures of her. Or keep them for three decades. And it certainly was not advisable to try to use the pictures to blackmail his ex-wife, the woman's sister, into redoing their divorce settlement. Especially because his ex-wife had gone to federal authorities, who recorded the blackmail attempt on tape.

The photos led to Peel's conviction for possession of child pornography, a conviction that Peel, once a successful lawyer, now is asking the Supreme Court to overturn. The justices are meeting Friday to consider accepting new appeals, including Peel's.

"This is a child pornography case that does not involve a child," Peel's lawyers told the court in their brief. They are claiming violations of the First Amendment and of the Constitution's bar against ex post facto convictions for violating laws that were not in place when an alleged crime occurred.

In the first place, they argue, the age of consent in Illinois was 16 in 1974, which they say means Peel's affair did not violate state law.

There also was no federal child pornography statute at the time. It was enacted in 1978 and, after being amended, now applies to sexual depictions of children younger than 18.

The Justice Department is urging the court to reject the appeal. Peel "is being punished for his possession of child pornography in 2006," acting Solicitor General Neal Katyal said in a court filing. In addition, the government disputes that the affair between Peel and the woman was legal at the time.

The court does not even need to consider any of those issues now, Katyal said, because the 7th U.S. Circuit Court of Appeals in Chicago has ordered the trial judge to redo Peel's prison sentence and throw out a bankruptcy fraud or obstruction of justice conviction that went along with the child pornography charge. Peel had been sentenced to 12 years in prison.

The 7th Circuit upheld the child pornography conviction, dismissing questions about whether prosecutors proved that Peel recalled in 2006 that the woman in the photographs was 16 at the time they were taken.

"He had known her since she was in fourth grade," Judge Richard Posner said in describing a series of contacts between them, "and years later had represented her in her divorce proceeding."

Peel, now in his mid-60s, was a prominent lawyer in Illinois' Madison County, northeast of St. Louis. He and Deborah Peel divorced in 2003 and, beset by financial difficulties, Peel filed for bankruptcy in 2005. A short while later, he approached his ex-wife, acknowledging the long-ago affair and telling her about the photographs.

Peel intimated he might make them public if his ex-wife did not let him out of his financial obligations to her. He eventually showed her the originals at a meeting that was being recorded by federal agents and included this exchange:

"So you resort to blackmailing me?" she said.

Peel replied, "There's nothing left. I'm down to no kids, no grandkids, no money."

Before he got into legal trouble, Peel scored several prominent courtroom victories. In a 1983 case, he won a $3 million judgment for Mary Bacon, a horse jockey who sued a local race track over injuries.

In 1990, Peel won a case before the U.S. Supreme Court. Facing sanctions for advertising himself as a certified civil trial specialist, Peel lost a state Supreme Court ruling that his advertising claim was misleading because it made him seem more qualified than other lawyers who do the same type of work.

But by a 5-4 vote, the U.S. Supreme Court ruled that states may not ban potentially misleading information if the information also may be presented in a way that is not deceptive. Peel did not argue the case in Washington.