WASHINGTON – The Supreme Court’s landmark gun rights ruling Thursday settled an old debate over the Second Amendment. It’s not all about muskets and militia service. Americans do, in fact, have an individual right to bear arms for self-protection.

But in striking down a handgun ban in Washington, D.C., a crime-plagued city with the nation’s toughest gun control laws, the court touched off a fresh debate over how far government can go to protect the public. Some regulations on possession and transfer of guns are “reasonable,” the court said in a 5-4 decision.

The question for courts, city councils and legislatures to sort out in coming years will be: Which restrictions pass muster? Gun rights advocates will be in court as early as Friday challenging handgun bans in Chicago and San Francisco’s public housing, and were scouring the books in Texas and across the nation for other ordinances to attack.

“Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose,” wrote Justice Antonin Scalia, joined by Chief Justice John Roberts, who decided to issue the ruling on the final day of the court’s annual term. The dramatic gesture reflected the intensity of the gun debate and the sweeping implications of a case that pitted public safety concerns against the right to bear arms.

This was the first time the court had explicitly said the Second Amendment protects an individual right to gun ownership, and was its first hard look at gun rights since 1939.

“Hallelujah. Praise the Lord and pass the ammunition,” said David Schenck, a Dallas lawyer who filed a brief on behalf of the Texas State Rifle Association and sister groups in 42 other states.

Dissenting Justice John Paul Stevens argued that the majority got its history wrong in saying the Second Amendment applied to individuals. He criticized the conservative wing of the court for failing to detail what restrictions they’d find acceptable.

The case was filed by Dick Heller, a security guard at the Federal Judicial Center who was refused permission to keep his handgun at his home in the nation’s capital. His attorney, Alan Gura, called the ruling a blockbuster.

“There are thousands of gun laws in the United States. Some of them are going to survive, and some of them might not,” he said.

Gun control advocates took some solace in the court’s embrace of “reasonable” restrictions.

“You can’t have gun bans, but you can’t have any gun, anywhere, any time,” said Paul Helmke, president of the Brady Center to Prevent Gun Violence. “By getting rid of the extremes, we can deal with this issue in the common-sense middle.”

At the National Rifle Association, which is preparing lawsuits in Chicago and San Francisco, chief lobbyist Chris Cox called it a “historic day.”

“This is an individual right that applies to all Americans, not just rich people, not just the elites,” he said, adding, “It’s not as if every gun law in the country is going to be struck down.”

Chicago Mayor Richard Delay called the ruling a “very frightening decision.” In Washington, Mayor Adrian Fenty warned that “more handguns in the District of Columbia will only lead to more handgun violence.” The mayor emphasized that the ban on carrying guns outside the home remains untouched.

Until now, Washington let only retired police register weapons, banned carrying a handgun without a license and required any firearm at home to be unloaded and disassembled or kept with a trigger lock. Taken together, Scalia wrote, that made it impossible for citizens to keep a gun at home “for the purpose of immediate self-defense” – an intolerable violation of individual rights.

Texas urged the court to strike down the district’s laws but also ratify the authority of states to impose some restrictions. Thirty other states joined its brief, authored by Ted Cruz when he was Texas solicitor general.

“The D.C. gun ban was the most extreme in the nation, and it was out of step with the judgments of the legislatures of all 50 states,” Cruz said Thursday, adding that whatever lawsuits emerge to test the limits of the new rules, sweeping societal changes aren’t likely. “In a state like Texas, the Legislature is not going to try to take our guns anytime soon.”

In a friend-of-the-court brief filed in February, Sen. Kay Bailey Hutchison, R-Texas, argued that the “militia” terminology in the Second Amendment was never meant to deny gun rights to individuals. Fifty-four senators and 250 House members joined her brief, along with Vice President Dick Cheney.

On Thursday afternoon, Hutchison was on the steps of the Supreme Court, beaming.

“Had it been affirmed – the D.C. law – you would have seen movements all over America to begin to ban handguns. So this was significant,” she said.

The ruling left intact restrictions on felons and the mentally ill, on carrying guns to government buildings or schools, and on the sale of military-style assault weapons.

“Not every gun control law is going to fail,” said Schenck, the Dallas lawyer, but “they will have to be carefully tailored to serve some interest apart from keeping free people away from guns.”