WASHINGTON - Three decades ago, at the dawn of municipal self-government in the District of Columbia, the city's first elected mayor and council enacted one of the country's toughest gun-control measures, a ban on handgun ownership that opponents have long said violates the Second Amendment.

All these years later, with the constitutionality of the ban now probably headed for a US Supreme Court review, a much-debated practical question remains unsettled: Has a law aimed at reducing the number of handguns in the District made city streets safer?

Although studies through the decades have reached conflicting conclusions, this much is clear: The ban, passed with strong public support in 1976, has not accomplished everything the mayor and council of that era wanted it to.

Over the years, gun violence has continued to plague the city, reaching staggering levels at times.

In making by far their boldest public policy decision, Washington's first elected officials wanted other jurisdictions, especially neighboring states, to follow the lead of the nation's capital by enacting similar gun restrictions, cutting the flow of firearms into the city from surrounding areas.

"We were trying to send out a message," recalled Sterling Tucker, the council chairman at the time.

Nadine Winters, also a council member then, said, "My expectation was that this being Washington, it would kind of spread to other places, because these guns, there were so many of them coming from Virginia and Maryland."

It didn't happen. Guns kept coming. And bodies kept falling.

Opponents of the ban, who won a March ruling in which the US Court of Appeals for the D.C. Circuit declared the law unconstitutional, said in a legal filing that the District's "31-year experiment with gun prohibition" has been a "complete failure." Meanwhile, D.C. officials, who have asked the Supreme Court to reverse the March decision, say the ban is a legally permissible public-safety measure that has saved lives.

Which side is correct depends on whose social science research is accurate. Although the city points to research indicating that street violence would have been worse without the law, opponents of the ban cite studies to the contrary.

"It's a pretty common-sense idea that the more guns there are around, the more gun violence you'll have," D.C. Attorney General Linda Singer said.

"One of the difficult things is, you can't measure what didn't happen," Singer said. "You can't measure how many guns didn't come into the District because we have this law."

But you can measure the violence that did occur, using the bellwether offense of homicide to chart the ebb and flow of crime in the District since the ban was enacted. And the violence here over those years was worse than in most other big cities, many of them in states with far less restrictive gun laws.