Last week Republicans in the Virginia General Assembly passed a measure that would write a debatable law into the state's Constitution. This is starting to become a bad habit.

A decade ago (and with some Democratic help) Republicans passed the Marshall-Newman amendment, which elevated the state's prohibition on gay marriage to constitutional status. Thanks to the Supreme Court that is now a dead letter, as well it should be.

The new measure would similarly elevate Virginia's right-to-work law. This is a bad idea, although the reasons are a bit complicated.

To begin with, right-to-work laws look like an improper governmental intrusion into worker-employer relations. They stipulate that Acme Widgets cannot require Joe the Mechanic to join a union as a condition of employment. But in a perfectly free market—one governed by the ideal of mutual consent—Acme should be able to make employment contingent upon any conditions it wants. If the conditions are too onerous, then it won't find enough employees, and it will lose the economic race to more kindly employers. (Why would an employer want to make union membership a condition of employment in the first place? Probably because an agreement with a union required it to.)

Of course, labor relations in the U.S. are very far from a perfectly free market. They are governed, among other things, by the 1935 Wagner Act, which sought to compensate for the "inequality of bargaining power between employees who do not possess full freedom of association or actual liberty of contract" and employers who could exercise the power of collective action through legal incorporation.

This might be fine as far as it went, but the Wagner Act didn't stop there. It also granted workers the right not to join a union—unless "such a right may be affected by an agreement requiring membership in a labor organization." Moreover, the Act stipulated that there could be only one bargaining representative for any given set of employees, and employers could be compelled to bargain with it. This meant that even if another union came along that could do more for Acme's workers, they couldn't avail themselves of that opportunity—by law.

Granting unions workplace monopolies like that was going too far for many people, especially in light of the widespread strikes that took place after World War 2. The result was the 1947 Taft-Hartley Act, which allowed states to pass right-to-work laws.

There are those—such as Sheldon Richman, writing in Reason—who argue that two wrongs don't make a right: The proper way to correct the excesses of the Wagner Act is to correct the excesses of the Wagner Act, rather than to address them through countervailing government interference at the state level. This makes excellent sense. Any other approach simply invites what has been called "kludgeocracy."

As Steven Teles explains in National Affairs, the word root is borrowed from computer programming: "A kludge is an inelegant patch put in place to solve an unexpected problem and designed to be backward-compatible with the rest of an existing system. When you add up enough kludges, you get a very complicated program that has no clear organizing principle, is exceedingly difficult to understand, and is subject to crashes."

On the other side are those—such as Shikha Dalmia, also writing in Reason—who argue that right-to-work laws make sense in the real world. For one thing, she notes, right-to-work laws achieve Pareto optimality: They make some parties better off without making other parties any worse off:

Wagner mandated closed shops [those requiring union membership as a condition of employment] and right-to-work laws ban closed shops. At best, employers are equally constrained under both scenarios. However, by making (union) dues payment optional, right-to-work laws vastly increase the freedom of workers, giving them more power to hold union bosses accountable for waste and corruption.

This also makes excellent sense. So Virginia's right-to-work law is, on balance, at least defensible and perhaps even good. (There is another debate about whether workers are better or worse off in right-to-work states when you look at wage levels, employment levels, and so on. But that is a consequentialist, pick-your-own-statistics debate well worth skipping here.)

Still, not every good idea belongs in the Constitution. It's a good idea to carry an umbrella if it looks like rain—but we don't need a constitutional amendment for that, do we?

As Democrats in the state Senate quickly pointed out, Virginia's right-to-work law has thrived, unmolested, for more than four decades now. It does not seem to be in even slight peril.

But it should not become part of the state Constitution even if it were in peril. After all, it is nothing but a response to federal legislation. Writing constitutional provisions to answer legislative mandates dilutes the purpose of having a constitution in the first place.

As the legal theorist H.L.A. Hart explained, generally speaking there are two kinds of rules. Primary rules dictate behavior ("Men shall wear hats in church"). Secondary rules are the rules about making primary rules ("Congress shall make no law. . . "). Constitutions are, or should be, made up of secondary rules. Right-to-work laws, however, are primary rules that proscribe certain behavior. They belong in the state code—not in the Constitution.

This column originally appeared in the Richmond Times-Dispatch.