Leading article: The conservative choice

Not even liberal utopians could have expected the conservative Mr Bush to pick one of their own. Instead, he has put forward a conservative to be sure, but one whose views are tempered by reality, and leavened by intelligence and a sense of humour. John Roberts is a more than satisfactory candidate to take the helm of an institution whose influence on American life is greater than that of any other except the presidency itself.

Supreme Court appointments, which are for life, arguably offer a president his best opportunity to leave a mark that endures far beyond his own time in the White House. Mr Bush is thus in an extraordinary position. Two vacancies have already arisen in two months and, given that two of the remaining seven Justices are over 80, others may follow before he steps down in January 2009. Conceivably, the US could be saddled with a "Bush Court" for a quarter century or more.

Judge Roberts was originally nominated in July following the resignation of Sandra Day O'Connor. Despite initial predictions of partisan war on Capitol Hill, it has seemed increasingly likely that he would be confirmed by the Senate with little opposition. There is no reason why his elevation to Chief Justice-in-waiting should change that dynamic.

Nor will the balance of the court, where conservatives generally have a 5-4 majority, be affected, since one reliably conservative Chief Justice is set to be replaced by another - although a lesson of Supreme Court nominations is that many presidents don't get quite what they bargained for.

The real question is, what sort of court will Judge Roberts preside over? Not least of a Chief Justice's powers is that of influencing which cases the high court will hear. This, in turn, has a huge bearing on the character of the court in its job of interpreting the constitution. Judge Roberts does not seem to be an unalloyed "constitutionalist" who believes that every word of that document is to be taken literally. But he appears to share his predecessor's view that the court must not "legislate" from the bench.

That, however, will be easier said than done. Gridlock on Capitol Hill has combined with America's ever-growing culture wars to turn the Supreme Court, whether it likes it or not, into the ultimate arbiter of burning social issues. This is the chalice handed to Judge Roberts.