The current debate does not involve handguns, whose registration has been required since 1934. Nor does it involve a variety of military-style weapons like assault rifles and sawed-off shotguns, which are banned outright. And the law’s repeal would not alter the requirement that gun buyers take safety courses and obtain a license.

But what it would do is hotly contested.

The current law requires the registration of the weapons themselves, rifle and shotguns, which account for 6.7 million of Canada’s 7.4 million registered guns, according to the Royal Canadian Mounted Police.

Many police forces say that registry data, which they consulted 3.4 million times last year, prevents killings by allowing them to seize guns from homes where serious domestic disputes have been reported.

And many police officials warn that without mandatory registration, their officers will lose the ability to seize illegal guns found in the possession of criminal suspects. William Blair, the Toronto police chief and president of the Canadian Association of Chiefs of Police, said that information from the registry allowed his force to seize 58 illegal guns in October alone.

Killings involving guns have declined significantly since the gun registry began but it is unclear how much of that the registry is responsible for. Homicide rates have been dropping in Canada since the 1970s. And the registry itself, delayed for years by bureaucratic and software problems, has been operational for only a few years, limiting the data available for analysis.

Many recreational hunters, farmers and Native Canadians who hunt for food consider the law a useless and intrusive burden. “From the beginning and still today, the feeling has been that it’s going to do absolutely nothing about reducing crime,” said Dale R. Garnham, the president of the Manitoba Wildlife Federation, a hunting and fishing group, who added that his members have felt “unduly harassed” by the registration process, which is similar to applying for a passport.

Greg Farrant, a lobbyist for the Ontario Federation of Hunters and Anglers, said that gun license records are sufficient for the police to determine if guns are likely to be in, say, a home that is about to be raided. And, like many critics, he cites the cost of the registry, nearly $1 billion to set up, as a reason to dismantle it.