As Barack Obama and John McCain offer contrasting approaches to issues from health care to energy independence to national security, it's worth remembering that Congress has more control over those matters than the president. The president's choices can have far more impact on the third branch of government — when it comes time to appoint justices to the Supreme Court.

As Barack Obama and John McCain offer contrasting approaches to issues from health care to energy independence to national security, it's worth remembering that Congress has more control over those matters than the president. The president's choices can have far more impact on the third branch of government — when it comes time to appoint justices to the Supreme Court.

The recent spate of rulings from the high court illustrates just how pivotal those choices may be in the next four to eight years. Landmark rulings such as upholding the right of habeas corpus for Guantanamo detainees and striking down the death penalty for child rapists were decided on 5-4 votes.

On Thursday, the court ruled — again, 5-4 — that the Second Amendment to the Constitution confers an individual right to own and keep guns — breaking with the long-held position that the right is a collective one limited to organized militias.

As is often the case, this ruling is more significant for what the court did not say than for what it did. The court has a long and appropriate tradition of avoiding decisions it does not have to make, leaving those questions for another time and another case.

So it was Thursday. Justice Antonin Scalia, writing for the majority, said the Constitution does not permit an outright ban on keeping guns in the home, but he stressed that the ruling should not "cast doubt on long-standing prohibitions on the possession of firearms by felons or the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings."

Those who insist that laws banning guns from schools are unconstitutional may wish to take note.

The court also remained silent on government licensing of firearms, because the D.C. security guard who challenged the handgun ban did not raise the issue in his lawsuit.

These and other lesser restrictions on gun ownership will now be the subject of new court cases. Gun rights supporters say they will challenge gun restrictions at the local, state and federal level. Some of those cases ultimately will wind up before the Supreme Court — but not necessarily the same Supreme Court.

The court's two oldest justices — John Paul Stevens, 88, and Ruth Bader Ginsberg, 75 — were in the majority on the Guantanamo ruling and the death penalty decision and in the minority on the gun case. It is entirely possible that one or both could retire in the next four years.

If Obama is the next president, he is unlikely to alter the conservative majority on the court because Scalia (72), Clarence Thomas (60), Samuel Alito (58), John Roberts (53) and Anthony Kennedy (71) are young enough to serve for the foreseeable future. If McCain wins, however, he could have the opportunity to solidify conservative control of the court for decades to come by replacing Stevens or Ginsberg or both.

Voters, regardless of where they stand on the court's recent rulings, should keep that in mind as they watch the campaign unfold.