The Bush administration ought to go back to the drawing board with the plan it unveiled this week to tighten security clearances. While the plan closes some loopholes, it violates certain rights and guarantees that government and defense workers and job applicants have held for 29 years.

The executive order would require more thorough investigations for initial clearances. It also would require a new investigation every five years for those with "top secret" clearance, and every 10 years for those with "secret" clearances.Updating security clearances is a prudent idea, since several employees recently arrested for selling secrets have held security clearances, but had not been re-investigated for many years.

There are two serious problems with the new rules, however. One is that the criteria for deciding if a person is a security risk appear to be far too broad and too vague.

For example, security officers would decide if an applicant has "exploitable vulnerabilities." These may include alcohol or substance abuse, criminal activity, exploitable sexual conduct, or mental problems. Those are acceptable concerns. But the rules also would question "financial stability" and something described as "indiscreet behavior," broad areas that could mean almost anything.

Worse, if a clearance application is turned down, the rejection would not give any reasons, rights to appeal would be curtailed, and the person affected would never know why or have a chance to correct erroneous information.

These are not minor objections. There are 2.8 million government employees and 1.1 million defense industry workers whose jobs require security clearances.

It would be better to keep most of the present system in which a written statement giving the reasons must accompany denial of a security clearance, appeals are allowed, and damaging material can be challenged.

In the pursuit of more protection against spies, let's not sacrifice the liberties and due process guarantees that this nation is supposed to stand for.