When the case of District of Columbia v. Heller was before the Supreme Court, Mayor Bloomberg filed a brief in support of the District’s handgun ban, arguing that a militia-only interpretation of the Second Amendment was necessary to keep New York City’s gun laws intact. On Thursday, when the Supreme Court ruled against Mr. Bloomberg’s position, the mayor claimed that the ruling was a “benefit” and would not affect any New York City laws. His claim was half-right. It is a benefit, but it’s unlikely that it will not affect any New York City laws. In most of America, Heller will have little effect on state and local laws, because the vast majority of states already have an individual right to arms in their state constitutions. Illinois and California are two of the states that don’t have a right to handguns; suits have already been filed challenging the handgun ban in Chicago and the S.F. ban on firearms possession by public housing residents. Those cases will help decide whether the Second Amendment is enforceable against state and local governments or only against the federal government

New York’s state Constitution has no right to arms, but the Civil Rights Law does. The Civil Rights Law begins with a Bill of Rights. Article 4 declares: “A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms cannot be infringed.” It is identical to the Second Amendment of the United States Constitution, except that New York follows modern standards for capitalization and punctuation, and says “cannot” instead of “shall not.”

As a Monroe County court accurately observed in the 1994 case Citizens for a Safer Community v. City of Rochester, “The Courts of this State have concluded that the language of federal law interpreting the Second Amendment (which is identical in its language to Article 2, section 4 of the Civil Rights Law) should be used in interpreting the provisions of this state law.”

Some New York courts have interpreted the New York right to arms restrictively, but these decisions were explicitly based on misunderstanding of the same language in the Second Amendment. The cases treating the Civil Rights Law as almost meaningless are of dubious validity now that Heller has made is clear that “the right of the people to keep and bear arms” is a broad and important individual right.

The New York City law which most obviously violates the right to arms is the complete ban on air guns. The venerable Daisy Red Ryder BB gun is contraband. Heller and the Supreme Court’s previous major Second Amendment precedent, United States v. Miller (1939) forbid the prohibition of arms “typically possessed by law-abiding citizens for lawful purposes.”

Air guns are ubiquitous almost everywhere except New York City, and are used almost exclusively for law-abiding purposes. Pursuant to Heller, regulation of air guns might be fine, but prohibition of all air guns is not.

Unlike firearms, air guns (which shoot small BBs or pellets) can be safely used inside an apartment or house. An old sofa cushion is a safe backstop. In a city where target ranges are few and expensive, air guns offer a practical way for people to practice safely with a gun. The right to arms necessarily includes the right to practice arms safety.

New York City bans magazines (ammunition clips) which hold more than 17 rounds. Whether the ban is consistent with Heller is debatable. Clearly inconsistent is the ban on any magazine which protrudes below the grip of the gun. The most common handgun in the United States is the Colt 1911 pistol, and the variants made by many other companies. The pistol’s magazine holds 7 rounds. Some after-market magazine companies make slightly larger ones, which hold 8 or 9 rounds. These magazines extend a half-inch or less below the grip.

There’s no public safety benefit to allowing guns with 17 rounds stored within the grip, but banning guns with 8 rounds because of a quarter-inch protrusion below the grip.

Regarding gun carrying, Heller might, arguably, mean that New York City would have to follow a similar policy to Connecticut (and 39 other states): issue permits to carry a concealed handgun for lawful defense if the applicant is over 21, and passes a fingerprint-based background check and a safety class.

At the least, Heller indicates that gun carry licensing may not be “enforced in an arbitrary and capricious manner.” This is a problem for New York State’s carry licensing law, as Suzanne Novak detailed in a 1998 article in the Fordham Urban Law Journal. New York state law sets essentially no standards to guide local officials in deciding whether to issue carry permits.

The problem is acute in New York City. Celebrities, the ultra-wealthy, and the politically influential get carry permits. But many of the people who need them the most — such as stalking victims, or crime witnesses who have been threatened by the criminal’s friends — often do not. Even if New York City is not required to go as far as Connecticut, the City does need much less favoritism and much more objectivity in its administration of carry permits.

Mr. Kopel is an associate policy analyst with the Cato Institute, in Washington, D.C., and has taught the “Gun Control and Gun Rights” course at New York University Law School. He was part of the team of four lawyers presenting the oral argument to the Supreme Court in Heller.