BOTH BUSINESS and labor have been cranking up their supporters for today's debate in the House on a bill to amend the National Labor Relations Act. Listening to labor representatives describe the legislation you might think it justly punished genuinely evil employers and gave workers their just entitlements and rights. Listening to business people describe it, you might think this was a simple power grab by unions out to destroy employers who get in their way. As in most matters of this kind, not all virtue is on one side. The bill is neither as good or as bad as it has been depicted, and it falls far short of providing the comprehensive reform that the labor laws need.

The bill has two valid central themes. One is that the procedures of the NLRB, especially those concerning union representation elections and enforcement of NLRB orders, are too cumbersome and time consuming. Anyone who watched the NLRB with a degree of detachment knows this is true: the possibilities for delay seem endless and the most simple issues can become incredibly complex. The other theme of the legislation is that the penalities now imposed on employers who defy the law are inadequate. This also is true: the need to strengthen penalities was underlined recently in the J. P. Stevens case when a federal court said it had "grave doubts" about its ability to enforce the labor law against those who persistently break it.

But we have doubts about the way in which the bill before the House attempts to remedy those problems. It would impose, for example, fixed and short waiting periods before representation elections - a useful idea - but it would not give the NLRB enough flexibility to extend those periods in extraordinarily difficult cases. And it would makes the loss of government contracts the ultimate sanction against employers who are persistent and flagrant violators of the law. While it is true that the government should not be doing business with a persistent law-breaker, there ought to be other ways to compel compliance. Taking away government contracts punishes workers as well as companies and may sometimes leave untouched the corporate officers who are responsible for the wrongdoing.

Beyond all this, the legislation being debated today doesn't consider the other side of the coin. Employers are not the only malefactors in labor disputes. Unions, too, sometimes break the law. This bill, put together by the administration, its friends in the labor movement and their friends in the House, addresses only half of the problem. Perhaps some of its shortcomings can be cleaned up as (and if) it progresses through Congress. But if the legislation passes in anything like its present form, Congress will only have strengthened the labor law partially and selectively and will have left a great deal undone. That is not what you would call a decent job of reforming the nation's labor laws.