The Supreme Court last week affirmed that the Second Amendment protects the right to bear arms. For gun advocates, so far so good.

But a sharp-eyed Wall Street Journal reporter picked up on a clause in Antonin Scalia’s opinion – in a footnote, no less – that could mean the ruling is far less sweeping than it appears.

The crucial words: “… incorporation, a question not presented by this case …”

In Supreme Court parlance, incorporation is the practice of requiring state governments to honor the liberties guaranteed by the Bill of Rights. The Bill of Rights was originally a curb on federal power only. But after the Civil War, the 14th Amendment forbade states from depriving “any person of life, liberty, or property, without due process of law …”

Citing this clause, the court later began ordering states to guarantee freedom of speech, protection from unreasonable police searches, etc.

But the incorporation of the Second Amendment is an open question, especially if Scalia says it’s an open question. The Wall Street Journal noted that he had earlier written that the Second Amendment “is no limitation on arms control by the states.”

The liberals on the court are more inclined, as a group, to order states around. But all four of them argued that the Second Amendment doesn’t provide an individual right to firearms.

So if Scalia and potentially like-minded justices aren’t inclined to incorporate the right to bear arms, no one will be telling the states they can’t control guns to their hearts’ content (within the limits of their own constitutions).

Which means Thursday’s decision might apply only to acts of Congress and the District of Columbia. For the Second Amendment crowd, that would make for a bitter victory.