Worker freedom faces an existential threat. In courts across the country, organized labor has launched a coordinated legal assault against state right-to-work laws, which enable workers to hold a job without being forced to join or pay dues to a union. Unions' transparent hope is that a possible liberal majority on the U.S. Supreme Court in the near future will eliminate this freedom and strengthen the labor movement after years of declining membership and influence.

This campaign stems from organized labor's recent policy losses in state capitals. The past half-decade has seen four states -- Indiana, Michigan, West Virginia and Wisconsin -- pass right-to-work laws. In all, 26 states have now strengthened worker freedom for anyone who holds a job within their borders.

But rather than changing the minds of legislators and voters, labor unions and their allies have filed lawsuits in three of the four recent states which enacted right-to-work laws, as well as in Idaho. The central claim is that since unions often represent workers who have opted out of union membership (so-called "free riders") as well as their dues-paying members, these states have created unconstitutional "takings" of unions' property - namely, a portion of non-union workers' paychecks.

It's ironic that labor unions have flocked to this argument, since unions are challenging a provision that they previously championed: the right to exclusive representation, forbidding individuals from negotiating their own contracts. Their sudden shift likely reflects their growing desperation. After all, union membership has fallen from over 30 percent in the 1950s to a mere 11.1 percent last year, with only 6.7 percent in the private sector. Organized labor is looking for some way to stanch the bleeding.

But unions' legal argument is specious. Right-to-work laws involve no "takings" as defined by the Fifth Amendment. To the contrary, such laws prevent the forced taking of a worker's pay without his or her consent. Labor's logic rests on the frightening assumption that wages belong foremost to unions rather than to the workers who earned them.

One federal court has already rejected the unions' argument. In 2013, the challenge to Indiana's right-to-work law reached a federal district court, which upheld the law the following year. The Seventh Circuit Court of Appeals subsequently agreed.

In Wisconsin, unions filed in state courts so as not to run into the Seventh Circuit again. West Virginia's challenge is also in state courts. The Idaho lawsuit, however, is in the federal courts, in the jurisdiction of the famously liberal Ninth Circuit Court of Appeals. The pro-union magazine In These Times called this case "particularly exciting."

What looks like a scattershot strategy is actually a calculated campaign. Unions have pinned their hopes on two or more courts reaching different conclusions, pressuring the Supreme Court to step in and provide clarity. And with the court's ideological balance very much in question following the death of Justice Antonin Scalia, a ruling ending right-to-work is a depressingly real possibility.

But any ruling by the Supreme Court is at least a year away, probably longer. So state lawmakers should begin taking proactive steps to protect worker freedom immediately.

The easiest solution would be for state lawmakers to enact what's known as "worker's choice." Developed by Michigan's Mackinac Center for Public Policy, this simple reform would ensure that union contracts don't cover employees who opt out of union membership, allowing individuals to represent themselves. This would instantly eliminate the issue of "free riders" while still protecting the worker freedom that comes with right-to-work laws; a recent poll by the Nevada Policy Research Institute found that 67 percent of union members support this policy. Michigan state Rep. Gary Glenn introduced the first worker's choice bill in September.

Another solution is passing legislation establishing periodic union recertification elections, so workers can vote on whether or not they wish to have the union in their workplace. So far, Wisconsin is the only state that requires recertification elections, and only for public-sector unions. But its experience since implementing this requirement in 2011 is telling: Between 2013 and 2014, a third of the state's public-sector bargaining units either lost recertification elections or disbanded before one could be held.

States can pass recertification laws for public-sector unions immediately, but applying these reforms to the private sector will require action from Congress. The proposed Employee Rights Act, which has 160 co-sponsors, would be a good start.

Each of these reforms is worth passing on their own merits. The past few years have seen significant gains in worker freedom, benefitting millions of workers. Those gains must be protected and expanded in the face of unions' latest anti-worker assault.