Richard Wolf, USA TODAY 3:08 p.m. EDT June 8, 2015

WASHINGTON -- The Supreme Court refused to weigh in again Monday on one of its most controversial topics: the right to bear arms.

The justices declined to reconsider the rights of local governments to constrain that right -- upheld by the high court in two landmark decisions over the past decade -- by requiring that handguns be disabled or locked up when they are not being carried.

The high court left standing a San Francisco law imposing those restrictions, but Justices Clarence Thomas and Antonin Scalia dissented.

San Francisco imposed the limitation in 2007 under threat of a six-month jail term and $1,000 fine. The law was upheld by the U.S. Court of Appeals for the 9th Circuit, which ruled it did not violate the Supreme Court's prior cases allowing guns to be kept at home for self-defense.

Those include District of Columbia v. Heller, a 2008 case that upheld the right to keep handguns at home in federal jurisdictions, and McDonald v. Chicago, a 2010 case that extended that right to states and localities. The two 5-4 decisions were written by Scalia and Justice Samuel Alito.

San Francisco's ordinance is aimed at avoiding accidental tragedies. It requires that when handguns are not being carried -- such as at night, when their owners are asleep -- they be disabled with a trigger lock or kept in a locked container.

The city noted in its brief opposing the high court's review that "long" guns are not restricted and handguns can be kept loaded. It said keeping them locked up "reduces the risk of suicide and unintentional shootings, particularly among children and
teens," as well as making guns harder to steal.

A group of city residents who filed the suit, along with the National Rifle Association, argued the law renders gun ownership self-defeating by making the gun inoperable when an intruder bursts on the scene. The high court's 5-4 majority in Heller struck down the District of Columbia's trigger-lock requirement.

"San Francisco has no more right than the District of Columbia to force its residents to fiddle with lock boxes or fumble with trigger locks when the need to use a handgun for immediate self-defense arises," the challengers argued in their brief seeking Supreme Court review.

A coalition of 25 states sided with the city residents in urging the court to overturn the law. Otherwise, they said, "responsible citizens will be unable to possess operable firearms in defense of hearth and home."

That was at the heart of the Thomas-Scalia dissent.

"The law ... burdens their right to self-defense at the times they are most vulnerable -- when they are sleeping, bathing, changing clothes, or otherwise indisposed," Thomas wrote. "There is consequently no question that San Francisco's law burdens the core of the Second Amendment right."

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