New Jersey could soon become the fourth state to limit handgun purchases to one a month, a move aimed at fighting "straw" gun buyers who purchase weapons legally and pass them to criminals.

The plan, backed by officials in Camden, Newark, Jersey City and other cities, follows calls from urban leaders across the nation, including Philadelphia, to crack down on gun trafficking that they say fuels violence.

There is much debate over whether such laws work, however, and opponents say a limit would infringe on a constitutional right in a state that already has rigorous screenings for gun buyers.

The proposal won approval in the Assembly but faces a tough final test in the more evenly divided Senate. Gov. Corzine, who sponsored a similar plan in the U.S. Senate, has said he will "absolutely" sign the bill into law if it reaches his desk.

"How many guns does somebody need to purchase in a month?" Corzine asked.

Only California, Maryland and Virginia have one-gun-a-month restrictions. South Carolina had a similar law for nearly 30 years but repealed it in the face of criticism that it had proved ineffective.

Gov. Rendell called for a one-handgun-per-month measure in Pennsylvania, but it was blocked. Philadelphia approved its own version and saw it struck down in court.

In a December hearing, Bryan Miller, executive director of Ceasefire NJ, said the New Jersey bill would not stop gun trafficking in the state but would be an impediment. Buyers would be restricted to one handgun purchase every 30 days - up to 13 a year because of timing quirks. He said the limits would not apply to other guns.

"What we're talking about here is some sort of balance . . . between the privilege of a tiny minority of handgun owners in the state and the common good of public safety," Miller said. "We're talking about a light burden, if any."

But some law-abiding citizens buy several guns at once to avoid repeated waits for background checks, gun-rights groups say. New Jersey already has some of the toughest gun laws in the nation, according to the Brady Campaign to Prevent Gun Violence, a gun-control group. Pistol purchases can take weeks or even months, gun advocates say.

"This legislation makes it a crime to exercise a constitutional right to obtain handguns any more often than Big Brother dictates," said Scott Bach, president of the Association of New Jersey Rifle and Pistol Clubs.

New Jersey handgun buyers must obtain permits from local police and go through background checks, Bach said.

That lets police know when multiple purchases are made, he said.

"It's overkill in the extreme, based on the false and unsupportable premise that criminals and their surrogates buy their crime guns from Jersey dealers after marching down to police headquarters to volunteer and submit themselves for fingerprinting, background checks and extensive personal disclosure," Bach said.

But that's exactly what gun-control advocates say happens. Fingerprints and personal records help only after a crime is committed, Miller said.

Straw buys appear legitimate at first because criminals work with buyers who have clean records. Limiting such purchases, Miller said, could head off some crime.

He pointed to gun-tracing data from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) showing that 28 percent of "crime guns" in New Jersey were first bought legally in the state, a sign, he said, that approved purchases can still lead to violence.

Most of the national criticism related to straw purchases centers on states with softer gun laws, such as Pennsylvania.

There, the vast majority of 250 gun-trafficking arrests in the last two years were tied to straw buyers and the people who received the guns, said Al Toczydlowski, chief of the Philadelphia Gun Violence Task Force.

New Jersey Attorney General Anne Milgram and the ATF have launched a stepped-up program that requires local police to share gun-tracing information with the state and federal agency. So far, its only case has resulted in charges in May against five men whose original purchases were in Pennsylvania and who therefore would be unaffected by the pending legislation. Most crime guns in New Jersey come from other states.

Senate Majority Leader Stephen Sweeney (D., Gloucester) said New Jersey already had plenty of regulations.

"We get so many laws on the books now that we don't enforce, the fact that we continue to put more on doesn't make any sense," he said.

It is difficult to measure the impact of gun-buying laws in other states.

Virginia approved a one-gun-per-month limit in 1993. The Virginia State Crime Commission issued a report two years later saying the rule had not created an undue burden on gun buyers and had reduced the number of crime guns traced back to the commonwealth.

But advocates on both sides say the law has been watered down with exceptions since then. Gun-rights groups say that's because the law proved ineffective, while gun-control organizations argue that lawmakers bent to lobbyists.

In December, Mayors Against Illegal Guns - a national coalition of more than 300 municipal leaders, including Philadelphia's Mayor Nutter and Camden Mayor Gwendolyn Faison - ranked Virginia back near the top of states that are a source for crime guns.

In Maryland, police saw a drastic reduction in gun sales immediately after the state's limits went into effect in 1996.

Yet a 2001 study by the Johns Hopkins Center for Gun Policy and Research found only a slight decline in gun violence.

California has had a buying limit since 2000, but police there say its impact is difficult to measure because the state has so many other firearms restrictions. The Brady Campaign ranked California's gun laws as the most stringent.

New Jersey is second, though its urban leaders say guns are still a problem.

In 2006, Jersey City passed an ordinance limiting gun buyers to one purchase per month, but it was struck down in state Superior Court.

The rule "arbitrarily and capriciously burdens the rights of individuals who have absolutely nothing to do with crime and violence," a judge wrote.

State Sen. Sandra Cunningham, a Democrat who represents part of Jersey City, hopes to move a statewide limit through the Legislature.

"The point of this is that we want to prevent [straw purchasers] from buying the guns in the beginning, and then we won't have to worry about them afterwards," she said in testimony last month.

Such talk makes Dale Kopas, a self-described sportsman from Gloucester County, wonder what restrictions could follow. In Trenton, after a committee voted last month to advance the limit, he pulled a pack of cigarettes from his pocket and wondered: Would he someday be limited to one pack a month?

"I resent being put in the same category as gang-bangers," he said.

Contact staff writer Jonathan Tamari at 609-989-9016 or jtamari@phillynews.com.