WASHINGTON -- The U.S. Supreme Court agreed yesterday to decide whether Pennsylvania's policy of withholding newspapers and magazines from especially dangerous prisoners violates their First Amendment rights.

The court granted a request by Pennsylvania Attorney General Tom Corbett that it review a 2-1 decision in the prisoners' favor by the 3rd U.S. Circuit Court of Appeals, which emphasized that "prison walls do not form a barrier separating prison inmates from the protections of the Constitution."

Judge Samuel A. Alito Jr., President Bush's nominee to the high court, dissented in that ruling, writing that the restrictions imposed on prisoners in a Long-Term Segregation Unit were a "rational" attempt by prison authorities to change inmates' behavior.

The Long-Term Segregation Unit, formerly housed in the State Correctional Institution in Pittsburgh, is now located at the state prison in Fayette County and holds as many as 40 so-called Level 2 prisoners, who may not possess newspapers, magazines or photographs unless they are of a legal or religious nature. Also banned are family photographs.

In ruling for the prisoners, the 3rd Circuit said the Pennsylvania Department of Corrections had provided no evidence that the ban on publications "achieves or could achieve its stated rehabilitative purpose."

In his majority opinion, Judge Julio M. Fuentes also suggested that prison authorities could accommodate the Level 2 inmates' free-speech rights without an undue burden on prison resources. Either guards could monitor the distribution of newspapers or magazines, he wrote, or prisoners interested in reading periodicals could be escorted to a library, as they are when they want to consult legal reference works.

Overall, the appeals court majority held, Pennsylvania's policy could not withstand judicial scrutiny under a 1987 Supreme Court decision holding that restrictions on prisoners' rights be "reasonably related to legitimate penological interests."

In his dissent, Judge Alito said the restrictions met that test, which is considerably less demanding than the "strict scrutiny" with which the court evaluates most alleged infringements of constitutional rights.

If confirmed as a Supreme Court justice, Judge Alito is likely to follow the example of Chief Justice John G. Roberts Jr. and recuse himself from matters on which he ruled as an appeals court judge.

Yesterday, Mr. Corbett expressed optimism that the court would ratify Pennsylvania's policy. "The Supreme Court has repeatedly held that courts should give corrections officials substantial room to use their best professional judgment in managing the dangerous environment of a prison," the attorney general said.

Pittsburgh attorney Jere Krakoff, who is representing the inmates, said, "While this is a very small percentage of inmates affected, it does address an important right of free speech."

In another case related to the rights of those who have been incarcerated, the Supreme Court yesterday refused to review Florida's lifetime ban on voting rights for convicted felons, a case that would have had national implications for millions of would-be voters. The justices declined to hear a challenge to Florida's 19th-century ban, which applies to inmates and those who have served their time and been released.

Felons are kept from voting in every state but Maine and Vermont, although restrictions vary. The issue of voter eligibility got renewed attention after the 2000 presidential election, which was decided by fewer than 600 votes in Florida.

The Florida appeal had been closely watched, because lower courts have been fractured in similar voting cases. Minority and voting rights groups urged justices to hear the case.

The Florida law was contested in 2000 in Miami on behalf of people who have already completed their punishments, including probation or parole. Their appeal asked if restrictions can be challenged under the 1965 Voting Rights Act, which removed barriers to black voters.

Florida attorneys argued that states have authority to set their own policies. Congress, in enacting the voting law, did not have the power to "intrude so deeply into the sovereign right of every state to set qualifications for voting and to establish punishments for felons," Washington attorney Charles Cooper, representing Florida, said in the state's filing.