The Supreme Court will now examine whether a fatal three-drug cocktail most of the states use to execute inmates may violate the ban on cruel and unusual punishment.

Among the four key questions the justices will consider is whether states can execute an inmate if there is a "substantial risk" of pain and suffering through lethal injection.

By taking the Kentucky case, the justices are expected to provide a road map for judges across the country, including in California, where a San Jose federal judge has been reviewing the issue for more than a year.

"They decided to take the bull by the horns," said Ronald Matthias, a senior assistant attorney general in charge of California's death penalty appeals. "It is a very significant development, and we expect a very far-reaching and important decision which we'll obviously be bound by."

The Supreme Court review is likely to further delay California's effort to resume executing death row inmates.

Matthias would not speculate whether the court's intervention would halt the ongoing challenge in California by death row inmate Michael Morales, whose case has prompted Gov. Arnold Schwarzenegger to overhaul the state's lethal injection procedures.

U.S. District Judge Jeremy Fogel is scheduled to hold additional hearings on the Morales case in December and to tour a newly constructed death chamber in November. But some legal experts now expect the case may wait until the Supreme Court makes its ruling.

California has put executions on hold since early 2006 while Fogel has been reviewing Morales' lawsuit, which maintains the state's lethal injection method poses an undue risk of an inhumane execution for the more than 650 inmates on the state's death row.

John Grele, one of Morales' lawyers, said he would need to review the Kentucky case more closely to determine its effect on the California litigation.

But legal experts agreed the decision to hear the Kentucky case would have broad implications for states across the country, particularly given the scattershot results that have come from different courts asked to review the arguments of death row inmates.

In some states, executions have been put on hold, whereas other states have kept executing people despite nearly identical challenges pending in their courts.

The Supreme Court's decision to take the Kentucky case is "huge news" that should lead to a "de facto moratorium" on executions nationwide, Douglas Berman, an Ohio State University law professor and leading expert on the issue, said on his law blog. Berman does not expect a ruling until the end of the court's next term, in June.

Elisabeth Semel, head of the death penalty clinic at UC Berkeley's Boalt Hall School of Law, said the case is crucial to settling questions surrounding lethal injection but cautioned that the justices do not necessarily have to settle them all.

"The court is taking a bite of the apple," she said. "But how big a bite is not known."

"It puts Judge Fogel and other judges in the middle of this process in a position where they have to step back," she added.

A Supreme Court review of lethal injection has been brewing for years. Most states with a death penalty have turned to the method after similar legal challenges of alternatives, such as the gas chamber and the electric chair.

A federal appeals court declared California's gas chamber unconstitutional in the mid-1990s, prompting the switch to lethal injection.

In recent years, the Supreme Court has been repeatedly asked to review challenges to various states' lethal injection procedures but has steered clear of the central constitutional issue. The justices did make it easier for condemned inmates to file challenges, prompting a number of cases to unfold in states such as Missouri, Tennessee and Kentucky.

A federal judge in Tennessee recently put executions on hold there after concluding that the state's lethal injection method was too flawed. Fogel, in the California case, called this state's execution procedures "broken" but fixable.

In the Kentucky case, the state courts rejected challenges from death row inmates Ralph Baze and Clyde Bowling Jr. after a trial was held in 2005 to review Kentucky's execution method. It was the Baze and Bowling case the Supreme Court agreed Tuesday to hear.

Kentucky uses the same three drugs to put an inmate to death as California -- sodium thiopental to sedate the inmate, pancurium bromide to paralyze the muscles in breathing and potassium chloride, which stops the heart.

Lawyers for death row inmates say pancurium bromide conceals an inmate's suffering and masks the potential of the third drug, causing a searingly painful death.

One of the four issues the Supreme Court may address is whether it is unconstitutional to use those three drugs if other chemicals are available that pose "less risk of pain and suffering."

But legal experts say the court's ultimate ruling may focus more on how a state administers those drugs, rather than what drugs are used.

The Supreme Court, experts say, can instead clarify the standard for what amounts to a cruel and unusual execution and the obligations of states to administer the fatal drugs with proper safeguards.

All but one of the states with the death penalty and the federal government use lethal injection for executions. The only exception is Nebraska, which requires electrocution.

The standard method involves administering three separate chemicals: sodium pentothal, an anesthetic, which makes the inmate unconscious; pancuronium bromide, which paralyzes all muscles except the heart, and then potassium chloride, which stops the heart, causing death.

Attorneys for the two Kentucky men said at least half of the death row inmates facing imminent execution in the last two years have filed suit challenging the chemicals used in lethal injections. While various lower court federal judges have ruled on the issue, the Supreme Court has yet to decide it.

The suit, filed Wednesday in U.S. District Court in Philadelphia, charges that her political activities in Haverford, Pa., caused Cozen O'Connor to apply a double standard that prohibited her from using any firm resources such as phones and email for those activities. She said the firm placed no restrictions on male lawyers' political activities.

The suit says that instead of investigating the complaint, the firm instead tried to prove that she violated its policy about using firm resources for political purposes, a charge that she denies.

The suit was filed by attorneys Michael J. Salmanson, Scott B. Goldshaw and Katie R. Eyer of Philadelphia's Salmanson Goldshaw and names Cozen O'Connor, firm founders Stephen Cozen and Patrick O'Connor and partner Kevin Berry as defendants. Cozen O'Connor's lawyer, Abraham Reich of Fox Rothschild, said the firm has always provided the same opportunities regardless of gender and that the investigation into Biswanger's complaint was "fair and objective." He said the firm looks forward to refuting the charges in court.

Biswanger, an employment litigator, has worked at Rubin Fortunato & Harbison of Wayne, Pa., since December 2005.

Opponents of same-sex marriage applauded Tuesday's 240-page decision, calling it a victory for traditional families and noting that most appellate courts in other states have reached similar conclusions. They also promised to mount a legislative effort of their own, vowing an aggressive push to explicitly ban same-sex nuptials in the state Constitution.

The court's majority opinion rejected the plaintiffs' claim that the 1973 statute discriminates on the basis of gender. In addition, the court concluded that while marriage is a fundamental right, it is not a right extended to gays and lesbians under current state law.

Within hours of the decision, many of the same-sex couples who had served as plaintiffs in the legal challenge gathered out side a Bolton Hill church to express anger and disappointment with the court's ruling.

Lisa Polyak and her partner of 25 years, Gita Deane, the lead plaintiffs, said they would keep fighting for legal protections for their 11- and 8-year-old daughters -- security they said would only be guaranteed through marriage.

"I feel like this decision is needlessly cruel to gay and lesbian families," said Polyak, speaking through tears during a news conference at Brown Memorial Church. "I wish these judges would have to face our children today because I have to."

David Rocah, staff attorney for the ACLU of Maryland and one of the lawyers representing the plaintiffs, said that the decision, while disappointing, did not mark the end.

"This is not the first time that the courts have not gone our way in this and other civil rights battles and it won't be the last time," he said. "I believe the march of history in this country is indeed a march toward justice."

Though the majority opinion rejected same-sex marriage, lawmakers who have for years made unsuccessful attempts at barring the unions in Maryland's Constitution said a ban was needed now more than ever.

"I assure you the constitutional marriage amendment will be reintroduced this session," said Del. Donald H. Dwyer Jr., an Anne Arundel County Republican and leading same-sex marriage opponent in the House. "Without it, there's nothing to preclude a future legal challenge made on a different argument or a different basis. The legislature ought to have the courage and the desire to publicly vote on the issue of marriage."

Since Massachusetts became the first -- and remains the only -- state to allow gays and lesbians to wed in 2003, an explosive debate over same-sex marriage has played out in courts and state capitals nationwide. Cases are pending in California and Vermont, but Maryland had been eyed as a bellwether state because of its strong liberal leanings.

Twenty-seven states have voted to ban same-sex marriage in their constitutions, while a handful -- Vermont, Connecticut, New Jersey and New Hampshire -- have adopted civil unions, which confer some of the rights of marriage.

Maryland's journey to the national spotlight began in July 2004, when 19 gays and lesbians filed a lawsuit in Baltimore Circuit Court challenging the 1973 statute. In January 2006, Baltimore Circuit Court Judge M. Brooke Murdock held that the law was unconstitutional and discriminatory. The Attorney General's Office immediately appealed the decision. Last December, the Court of Appeals heard arguments.

The bitterly divided court was passionate in its opinions, with four judges supporting the majority, two penning dissents and one concurring in part and dissenting in part.

In the majority opinion, Judge Glenn T. Harrell Jr. wrote that the state has a legitimate interest in promoting opposite-sex marriage. But he also reminded lawmakers that they have the right to consider a law permitting same-sex marriages.

"In declaring that the State's legitimate interests in fostering procreation and encouraging the traditional family structure ... our opinion should by no means be read to imply that the General Assembly may not grant and recognize for homosexual persons civil unions or the right to marry a person of the same sex," he said.

Harrell was joined by judges Dale R. Cathell, Clayton Greene Jr. and Alan M. Wilner. Judge Irma S. Raker concurred in part and dissented in part. Chief Judge Robert M. Bell and Lynne A. Battaglia wrote dissenting opinions.

The majority opinion rejected the plaintiffs' claim that denying gay marriages is a form of sex discrimination. In fact, sex discrimination does not apply to individuals, only to groups, the court stated.

"The court was unusually clear in choosing the side that sex discrimination is only from the point of view of the group," said Julie Shapiro, an associate professor at the University of Seattle School of Law. While Washington's highest court reached a similar conclusion in that state's same-sex marriage case, it did not articulate it so clearly, she said.

"The court seems to be saying that discriminating because someone is lesbian or they are gay is not as big of a problem," she said.

While the court recognized that gays and lesbians face discrimination, it also notes that as a group they are not "politically powerless," and therefore not entitled to protections.

"It is clear that homosexual persons, at least in terms of contemporary history, have been a disfavored group in both public and private spheres of our society," the decision reads. "This court nevertheless finds that a history of unequal treatment does not require that we deem suspect a classification based on sexual orientation."

"I don't think that's true," said Jana Singer, a law professor at the University of Maryland who was among the 58 professors from the University of Maryland and University of Baltimore law schools who filed friend-of-the-court briefs supporting the plaintiffs. "I think the fact that same-sex couples are excluded form the hundreds of protections of marriage indicates they are not politically powerful."

In his dissenting opinion, Bell said the majority underestimates the societal barriers facing gays and lesbians. He compared denying them the right to wed to the bans on interracial marriage, which were struck down 40 years ago in the landmark U.S. Supreme Court case Loving v. Virginia.

"To be sure, there are important differences between the African American experience and that of gay men and lesbians in this country, yet many of the arguments made in support of the antimiscegenation laws were identical to those made today in opposition to same-sex marriage," Bell wrote.

In her dissent. Battaglia said her fellow judges offer no "principled basis" for denying the plaintiffs' sex discrimination claim. "In reaching this result, the majority breathes life into the corpse of separate but equal," she wrote.

Raker, meanwhile said she fa vored decision similar to that of New Jersey's highest court, which last year required the state to extend the rights and benefits of marriage to gay couples within 180 days, but left it up to the state legislature whether to call such unions "marriage."

The court's ruling -- coming on the heels of similar conclusions reached by the high courts of many other states -- suggests that advocates of same-sex marriage are going to need to turn to legislative action, said Carl Tobias, the Williams Professor at the University of Richmond School of Law.

Automakers General Motors Corp. and DaimlerChrysler AG -- which has since sold its Chrysler unit -- sued in 2005 to block the law, arguing that states do not have the authority to regulate the amount of CO2 released by cars, which is closely related to fuel economy.

Vermont is one of nearly a dozen states that followed California's lead in adopting the strict standard, which is tougher than federal rules and is intended to reduce the rise in global temperatures and changing weather patterns associated with greenhouse gas emissions.

The automakers argued that they could not meet the new standards, and in court testimony said they would have to pull out of the state as a result.