Last weekend, the European Common Market voted to drop its ban on new investments in South Africa in recognition of progress toward abandoning apartheid.

Earlier, Britain lifted most of its sanctions against South Africa for the same reason.Now it's time for the United States to follow suit.

The case for ending the sanctions - a case that became strong after President F.W. de Klerk launched his campaign of racial reforms - should become especially compelling Feb. 1.

That's when de Klerk is expected to scrap all but one of the remaining racial segregation laws - the one classifying every South Africa by race at birth. This final law is scheduled to be repealed following the adoption of a new constitution.

These steps should satisfy just about all of the conditions laid down by the United States in 1988 when it imposed sanctions in a triumph of good intentions over good judgment. Sanctions were a mistake because, as even white South African foes of apartheid keep noting, the trade restrictions hurt the very people they are designed to help - namely, South Africa's black majority.

But that's water over the dam. For now, eliminating the sanctions would serve expediency as well as justice. As South Africa phases out apartheid, it's only fair to start phasing out sanctions, too. Besides, with de Klerk coming under increasing criticism at home for winding down apartheid, he needs to be not just punished but rewarded.

One final point: As South Africa heads toward a greater voice for its black majority, the country also heads toward increased tribal violence. Will the world be as eager to condemn and punish black violence as it was to punish white injustice? Don't count on it.