WASHINGTON — When the U.S. Supreme Court in 2003 struck down a Texas law against same-sex sodomy, saying that the Constitution protected the right of “intimate conduct with another person,” dissenting Justice Antonin Scalia went into rhetorical overdrive.

Scalia warned that, having found that moral condemnation was not a compelling reason for making homosexual conduct a crime, the majority was opening the door to challenges to laws against bigamy, same-sex marriage, adult incest, prostitution, masturbation, adultery, fornication, bestiality and obscenity.

“Every single one of these laws is called into question by today’s decision,” Scalia thundered in his dissent in Lawrence v. Texas.

Now, a federal appeals court in Philadelphia is preparing to hear a pornography case from Pittsburgh that some conservatives consider the first step on the slippery slope that Scalia feared.

Other legal observers and gay rights activists disagree and predict that the appeals court will break the connection between a right of “intimate conduct” proclaimed in the Lawrence decision and a right of pornographers to sell their wares.

But whichever way the decision goes, the case promises to provide an early reading on whether the federal judiciary will rein in the Lawrence decision or allow it to sweep away other laws on sexuality.

The case now pending in the 3rd U.S. Circuit Court of Appeals concerns Extreme Associates, a Los Angeles-based company that provides sexually explicit materials through the mails and over the Internet. The government charged Extreme Associates with violating obscenity laws by distributing materials that, among other things, depicted women being gang-raped, defecated on and having their throats slit.

In late January, Pittsburgh-based U.S. District Judge Gary Lancaster dismissed the charge, citing, among other cases, Lawrence v. Texas. Under Lawrence, Lancaster wrote, “the government can no longer rely on the advancement of a moral code, preventing consenting adults from entertaining lewd or lascivious thoughts, as a legitimate, let alone compelling, state interest.”

Lawrence was one pillar of Lancaster’s ruling; the other was a 1969 Supreme Court decision called Stanley v. Georgia in which the high court ruled that individuals could not be prosecuted for consuming obscenity in their homes.

Although Lancaster invalidated obscenity laws “as applied” to Extreme Associates, the implication of his ruling was that all obscenity prosecutions were suspect.

The Justice Department appealed, and U.S. Attorney General Albert R. Gonzales warned that if Lancaster’s ruling prevailed the government would be hampered in prosecuting not just obscenity but also bigamy, bestiality and other conduct that offended “shared views of public morality.”

Cincinnati attorney H. Louis Sirkin, who is representing Extreme Associates and has an impressive track record in defending obscenity cases, said in an interview that he expects to prevail in the 3rd Circuit. But in a brief filed recently with the appeals court, the U.S. attorney for Western Pennsylvania, Mary Beth Buchanan, argued that Lancaster had “disregarded and misapplied a well-established body of constitutional law.” A number of legal observers agree.

Eugene Volokh, a First Amendment expert at UCLA law school, noted that in a 1972 case called U.S. v. Orito, the Supreme Court said that it had “consistently rejected constitutional protection for obscene material outside the home.” He also pointed out that in the Stanley ruling, the Supreme Court specifically said that it wasn’t overruling decisions outlawing the sale of obscenity.

As for the Lawrence v. Texas sodomy decision, Volokh said the connection with obscenity is thin.

“The reasoning in Lawrence focuses on the importance of certain relationships and of sex as an aspect of those relationships,” Volokh said. “But with regard to obscenity, where really it’s a matter of people consuming it for their own gratification without a relationship with another person, without interaction with another person, that’s something that Lawrence just doesn’t cover.”