The start of the U.S. Supreme Court's fall term is a much-anticipated event. This year, it is likely to receive more attention than usual, with a new justice being seated and conjecture that another plans to resign.

David Souter is no longer on the court, and this will be the first term for his replacement, Justice Sonia Sotomayor. It may be the last term for Justice John Paul Stevens, liberal icon of the court. The growing speculation that Stevens plans to retire next year was fueled by his recent decision not to select a full complement of clerks for 2010 — a strong signal that he doesn't intend to remain.

For the most part, however, all eyes will be on Sotomayor. Most of the court handicappers will be watching for early signs of how she might depart from the liberal voting record of her predecessor.

Sotomayor will be tested in one of the areas of greatest concern to liberals — free speech — at the very start of her tenure on the court. Sotomayor was opposed by some free-speech advocates, in part because of her vote in Doninger vs. Niehoff, in which the appeals court upheld the right of school officials to punish students for out-of-school speech — in what some considered a major blow to both the First Amendment and student rights.

Sotomayor's first free-speech case at the Supreme Court came even before the official beginning of the term. In a rare re-argument of a case, the justices convened court in advance of this month's opening to hear arguments in a case involving "Hillary: The Movie."

At issue in the case — a ruling is still pending — may be the viability of one of the major parts of campaign-finance law. The case is actually more compelling than the movie, a 90-minute diatribe against Hillary Rodham Clinton released by the conservative group Citizens United during her 2008 presidential bid. The Federal Election Commission ruled that the film was "prohibited electioneering communication."

Sotomayor's vote, although unlikely to determine the case's outcome, may offer insight into her thinking on the First Amendment and whether corporations enjoy free-speech rights analogous to individuals.

At the start of the fall term, Sotomayor will be tested in yet another case raising fundamental speech rights. The court will hear United States vs. Stevens, involving a federal law making it illegal to sell photographs and films of the maiming and killing of animals.

Robert J. Stevens of Pittsville, Va., was convicted under the law for selling videotapes of fighting pit bulls and sentenced to 37 months in prison. However, the appellate court struck down the law as unconstitutional, holding that there is no exception to the First Amendment for animal cruelty as there is for obscenity. The government is seeking to get the court to create another exception to the First Amendment, in what free-speech advocates fear will be part of a continued erosion of this fundamental right.

The case will test Sotomayor's commitment to principle over the prejudicial elements of the crime. The justices will clearly find Stevens and his films of dogfights repugnant. However, there has been a line drawn under the First Amendment in which criminal conduct can be prosecuted even as speech is protected. The government can clearly arrest people for holding dogfights or organizing or transporting dogs for such fights. The question is whether selling material with such images is protected by the First Amendment if an individual did not participate in the criminal activity. The concern is that Congress will continue to add exceptions for areas viewed as offensive or cruel — abandoning a bright-line rule that has protected speech while allowing the prosecution of illegal conduct.

Whatever the outcome of these cases, one thing is clear: Court-watchers will not have to wait long to hear the voice of Sotomayor in the area of free speech. It could be a voice that resonates for decades for citizens and the First Amendment.

Jonathan Turley is a law professor at George Washington University. He wrote this commentary for the Los Angeles Times.