THE SENATE has finally taken up the labor-law reform bill - and ought to pass it. The basic purpose of the bill is to uphold a simple and fundamental principle that no one should be permitted to profit by violating or evading the law's requirements. This legislation would provide little in the way of new rights or privileges to the National Labor Relations Board's presents procedures and - an essential point - increase the chances that its orders would be put into effect promptly.

This legislation is essentially aimed at the small but conspicuous minority of employers who exploit present procedures to procrastinate, sometimes interminably, in meeting their legal obligations. The bill would, for example, set firm time limits for representation elections. If the union wins an election, present law requires the employer to bargain in good faith. Sometimes companies are recalcitrant. Then the union has to go back to the NLRB, which - months, or sometimes years, later - issues an order. But an NLRB order is not self-enforcing. If the employer chooses to ignore it, nothing happens until somebody goes to court. The bill wouldn't abridge anybody's right of appeal. It would just speed up the process.

Much of his bill comes out of organized labor's long struggle with one textile manufacturer, J.P. Stevens and Company. The company has repeatedly been found in violation of the law and several times has been held in contempt of court. It prefers to pay fines rather than to follow the law. The bill tries to strike directly at Stevens with a blacklist clause forbidding goverment purchases from companies in violation. But blacklisting is an ugly device and, as a purely practical consideration, there may be other willful violaurs in the future that do not sell to the government. The Senate would be wise to delete the blacklist clause altogether and substitute other weapons, like escating fines.

The basic defect of this bill, as we have repeately argued, is its disproportionate attention to the unions' troubles. It displays inadequate concern for the rights of individual workers. But the bill has already been through the House, and there is little opportunity now for any broad revision. The question is whether the bill, as it stands, would improve American labor law.

The bill's opponents, including most business organizations, believe that it will lead to hugely successful union organizing drives. That seems unlikely, when you consider the present state of the unions. The proportion of the labor force that belongs to unions has been declining for a quater of a century. The unions look to this bill to help them at last stop the erosion. But the causes run far deeper than this rather modest reform can reach. Unions have always had great difficulty organizing white-collar workers - with the notable exception of goverment employees - and the service industries. That's where most of the growth in employment now lies. As for the unions themselves, their leadership is aging and not very flexible in adapting to a changing economy.

Both unions and employers have loaded this bill with symbolic freight far out of proportion to anything that it will accomplish. The bill has became a test of labor's strength and status in American politics. It has become in a queer way, a vote on the moral worth of the unions versus the employers. That is why the Senate is now gloomily settling down to another siege of filibustering and cloture votes - one that will go on, apparently, for weeks. The point to remember, as it goes groaning and droning along, is that the bill is narrower than either side would have you think - but on balance it is worth having.