In another dramatic victory for firearm owners, the Supreme Court has ruled unconstitutional Chicago, Illinois' 28-year-old strict ban on handgun ownership, a potentially far-reaching case over the ability of state and local governments to enforce limits on weapons.

A 5-4 conservative majority of justices on Monday reiterated its two-year-old conclusion the Constitution gives individuals equal or greater power than states on the issue of possession of certain firearms for self-protection.

"It cannot be doubted that the right to bear arms was regarded as a substantive guarantee, not a prohibition that could be ignored so long as states legislated in an evenhanded manner," wrote Justice Samuel Alito.

The court grounded that right in the due process section of the 14th Amendment. The justices, however, said local jurisdictions still retain the flexibility to preserve some "reasonable" gun-control measures currently in place nationwide.

In dissent, Justice Stephen Breyer predicated far-reaching implications. "Incorporating the right," he wrote, "may change the law in many of the 50 states. Read in the majority's favor, the historical evidence" for the decision "is at most ambiguous."

He was supported by Justices John Paul Stevens, Ruth Bader Ginsburg and Sonia Sotomayor.