The Supreme Court ruled yesterday that companies may legally charge wholesalers and retailers different prices for the same product -- but only if such differences constitute "reasonable reimbursement" to the wholesalers for the services they perform and the higher costs they incur.

Such price differences, known as "functional discounts," are a lower price offered to a purchaser -- usually a wholesaler -- that performs services, such as transportation and storage, that the seller performs for other retail customers.

The federal Robinson-Patman Act prohibits "price discrimination" -- charging different buyers different prices for the same product -- unless the differential is justified by the cost of production or is necessary to meet competition.

The provision of functional discounts to wholesalers is a popular practice in a number of industries. But until yesterday, the court had never directly addressed the question of whether such discounts are permitted under Robinson-Patman.

Yesterday's decision in Texaco Inc. v. Hasbrouck involved discounts given by Texaco to two distributors in Spokane, Wash.

Gas stations supplied by the distributors increased their sales volume dramatically, while independent Texaco retailers in Spokane -- who paid higher prices for the same gasoline -- suffered.

Twelve service station dealers sued Texaco, complaining that the distributor discounts violated the Robinson-Patman Act.

The company was held liable for treble damages amounting to $1.35 million.

In an opinion by Justice John Paul Stevens, six members of the court said that, as a matter of law, functional discounts were not on their face illegal.

But the court was unanimous in its judgment of the Texaco case, saying that there was "no substantial evidence" that the oil giant's discounts to its distributors "constituted a reasonable reimbursement for the value to Texaco of their actual marketing functions."

In fact, Stevens said, there was an "extraordinary absence of evidence to connect the discount to any savings enjoyed by Texaco."

For example, he noted, one distributor was separately compensated for hauling, and neither of the distributors maintained any significant storage facilities.

Although Justices Antonin Scalia, joined by Justice Anthony M. Kennedy, concurred in the result, they refused to "adopt the Court's reasoning, which seems to create an exemption for functional discounts that are 'reasonable' even though prohibited by the text of the {Robinson-Patman} Act."

Justice Byron R. White concurred separately in the decision.