The Supreme Court is called upon often to interpret congressional intent. But the court's interpretation of a matter close to home -- or, more precisely, to and from home -- appears to be a closely guarded secret.

When Justices Byron R. White and Sandra Day O'Connor made the Supreme Court's annual pilgrimage to Congress last year to make a pitch for the court's $17 million budget, they asked for authorization to use the court's car pool to take the nine justices to and from home each day.

Congress gave them the authority to use the court's vehicles, including six Lincoln Town Cars, for home-to-court travel, essentially authorizing what several of the older justices had been doing.

But the Senate emphasized that the approval of cars and court police drivers was "to meet legitimate security needs" and insisted its language "does not provide a blanket authorization of home-to-work transportation."

Congressional sources said the language does not authorize the justices' use of the cars after hours for personal reasons.

Knowledgeable sources said that such uses have included taking O'Connor to the Arena Stage to see "The Good Woman of Szechuan"; picking up the daughters of Justice Harry A. Blackmun at National Airport; fetching Chief Justice Warren E. Burger's daughter's laundry from the cleaners; ferrying friends about town, and dispatching the court station wagon to Baltimore-Washington International Airport to help White with his luggage and take him to his Northern Virginia house.

The court's press officer said court officials would not discuss the issue because it affects decisions involving the security of the justices. But one source who has done a lot of driving for the justices said: "They'll say it's for security, but it's really a taxi service."

It's not clear whether O'Connor, joined by Justice Lewis F. Powell Jr., will talk about transportation when they make the annual budget pilgrimage to the Hill today, according to the press officer.