If the parental leave bill were not so very wrong in principle, it might be defended on its merits, but wrong it is. Mr. President, prepare your pen for a veto.

The bill approved on March 20 by the House Education and Labor Committee is no improvement upon the almost identical bill that drew a veto last summer. This year's version, in both House and Senate, would require employers to grant up to 12 weeks of unpaid leave so that an employee could tend a newborn child or take care of a seriously ill member of the immediate family.Small businesses would not be affected by parental leave: The bill applies only to those employers with 50 or more employees. Under this limitation, 95 percent of all employers would be exempt, but half of all workers in the non-farm labor force would be eligible for the permissible leave. During periods of leave, a worker's health insurance would continue; seniority would not be adversely affected, and those who took parental leave would be guaranteed their jobs on their return.

So described, the bill cannot fairly be described as a terrible imposition on employers. By one estimate, the continuance of health benefits might cost businesses as much as $600 million a year, but this is an expense that would be borne anyhow. The number of workers actually taking the whole 12 weeks presumably would be small. Not many working families are geared to go three months without a paycheck.

Moreover, there is a certain appeal to conservatives in the declared purpose of protecting family values. It is a good thing for parents to nurture a newborn child. The serious illness of a wife, a husband or a parent is reason enough to justify personal care.

But marshaled against these considerations is an overriding objection: It is wrong in principle for the federal government to mandate this kind of benefit. The requirements imposed by the pending bill would usurp a function of collective bargaining and violate the idea of diversity.

In his veto message of June 29, Bush objected that the parental leave bill ignores the realities of today's workplace.

"Some employees may believe that shorter paid leave is more important than the lengthy, unpaid leave mandated by this legislation. Caring for a sick friend, aunt or brother might be just as critical to one employee as caring for a child is to another. In other cases, some employees may prefer increased health insurance or pension coverage rather than unpaid family and medical leave.

"Choosing among these options traditionally has been within the purview of employer-employee negotiation or the collective bargaining process. By substituting a `one size fits all' government mandate for innovative individual agreements, this bill ignores the differing family needs and preferences of employees and unduly limits the role of labor-management negotiations."

Precisely so. The pending bill sometimes is compared to long-established requirements under the Fair Labor Standards Act. The act fixes a 40-hour work week and prohibits an employer from compelling labor beyond that point unless overtime is paid. If the government may do that, why is it wrong for the government to mandate parental leave?

The analogy is flawed. In the one case we are dealing with laws of broad application serving universal social purposes. Parental leave is much narrower. A constitutional justification may be offered for a law that says no 12-year-old girl may work in a garment loft. No such rationale covers unpaid leave for "parenting" a baby.

In theory and in principle, ours is an economy in which labor and management enjoy wide areas of freedom to contract. The government's role, we believe, is largely a policeman's role. Employers may not ignore industrial safety; they may not hire children; they may not engage in fraudulent advertising; they may not transport adulterated goods.

The pending bill is quite different. Instead of saying "you must not," this bill says to employers "you must." What an employer must do, in the context of this bill, is none of the government's business.