There's an important issue bubbling up in American politics: any Republican president elected in 2016 could very likely accelerate the decline of private-sector labor unions in America.

Since the mid-1940s, American states have been split between those with "right-to-work" rules that make union organizing difficult and those with legal systems that are friendly to union organizing. But in 2012, the two formerly union-friendly states of Indiana and Michigan went right-to-work, and were joined by Wisconsin in 2015. Now Wisconsin Gov. Scott Walker says he would take right-to-work nationwide as president, and it's unlikely he'd face much resistance from congressional Republicans if he did.

Democrats oppose such laws — Hillary Clinton has spoken recently about the importance of collective bargaining, and if anything, centrist Democrats have become more supportive of union rights as a necessary counterpoint to a trend of stagnating wages.

This is a fundamental disagreement between the two parties about how politics and the economy should be organized. And for the first time since the Truman administration, the stage is set for it to play out on a national political stage.

What do right-to-work laws do?

A little bit confusingly, right-to-work (RTW) laws do not establish a right to work. Instead, they prohibit certain kinds of contractual arrangements between employers and employees at unionized workplaces. It's easier to understand what RTW does if you first look at how things typically work in a unionized private-sector workplace in a non-RTW state.

First, you have to start a labor union and get it recognized as the bargaining agent for a specific class of workers. This isn't like setting up a staff softball team or other club at work; it's a formal process run by the National Labor Relations Board with important legal consequences. You can read all about it here.

Once the union is in place, it has to negotiate a first contract with the employer. In almost every case, one provision of that contract is going to be that every worker in the bargaining unit needs to either join the union (and pay dues) or else pay a "representation fee" to the union — the idea being that since all workers in the bargaining unit benefit from the contract's gains for workers, all should contribute to the union's work.

In an RTW state, these representation fee agreements are illegal. You can join the union and pay dues, or you can stay out of the union and keep your money.

What's the case against RTW?

One simple principled case against RTW is basic freedom of contract — why should the government prevent a union and an employer from agreeing to a representation fee if that's what they want to do? There's a particularly heavy irony in the fact that RTW rules are typically pushed by conservative politicians who valorize free markets in other contexts.

You don't necessarily hear this argument all that frequently, because the liberals who are most likely to oppose RTW rules aren't generally big boosters of unregulated markets and total freedom of contract. But as Sheldon Richman has written for Reason, there is an extensive history of libertarians opposing RTW rules, although in the present day libertarians are normally aligned with pro-RTW politicians.

A more standard argument from liberals is simply that RTW makes it too easy for people to free-ride. Letting people gain the benefits of unionization without paying their fair share makes it too hard for unions to secure the financial resources they need, and leads to the eventual unraveling of the union itself.

On a practical level, labor unions spend a fair amount of money on political activism, typically in support of Democrats. Consequently, Democratic Party politicians tend to dislike measures that would deprive unions of funds.

What's the case for RTW?

The standard libertarian counterargument, made by Shikha Dalmia, to the freedom of contract view is that the National Labor Relations Act is itself "an abomination, which unduly restricts the contractual freedom of both companies and labor."

She lays out the case against the NLRA thusly:

The act not just severely restricts the means that both sides can deploy to extract the best possible deal from the other—employers are barred from, for example, asking prospective employees to sign yellow-dog contracts promising not to join unions and unions are barred from engaging in secondary boycotts or wild cat strikes. It also mandates a single workplace arrangement whereby only one union has the legal monopoly to represent all workers in negotiations. Once the government certifies this union, workers have to pay dues to it and employers have to negotiate with it in good faith.

In this view, RTW is a necessary corrective — not an ideal solution, but a means of pushing back against a flawed overall labor landscape. RTW carves out a necessary space of individual freedom, in which workers don't have money confiscated against their will to be spent as union bosses see fit.

On some level, then, the push for RTW is grounded in a sense that labor unions, as currently constituted in the United States, are a kind of illegitimate institution. Employees should not be able to band together and force employers to negotiate with them collectively. But given that they can, individual employees should at least be able to opt out of supporting the process financially.

Do RTW laws boost the economy?

Unfortunately, since the divide over RTW is so interlinked with other political and economic issues, it is very difficult to study this in a rigorous way.

A 2013 Congressional Research Service report finds that RTW states have faster job growth but lower wages than non-RTW states. But this is mostly just another way of saying that the entire South is RTW and the whole Northeast and Pacific Coast are not. The Northeast and California have much higher housing prices than the Sun Belt, so they experience slower population (and therefore job) growth and disproportionately attract affluent skilled workers.

The recent spate of new right-to-work laws should provide some interesting evidence for researchers. One could, for example, look at counties on either side of the Indiana-Illinois border and see if their fortunes have diverged in some interesting way since Indiana went RTW. But this research hasn't been done yet.

Could RTW go national?

Passing a federal right-to-work law has not been a point of emphasis for the GOP congressional leadership or for Republican presidential contenders. But Walker signed an RTW law in Wisconsin, and now says he favors a federal one. Jeb Bush was governor of Florida, an RTW state.

More important than any particular statement, however, is the trend. For a long time the country was in a bit of a cold war scenario, where unions were sufficiently strong in non-RTW states that Republicans didn't seriously try to kneecap them, and sufficiently weak in RTW states that Democrats didn't seriously try to amend labor law in a more union-friendly direction. Since the 2010 midterms, that calculus has changed. Republicans have discovered that they can run and win in Midwestern states while pushing for anti-union measures. And with every RTW victory, unions grow weaker and less able to resist additional anti-union measures.

Consequently, there's no real reason Republicans wouldn't try to follow a 2016 electoral win with an RTW push in the subsequent Congress. Depending on the exact details of the election results, Democrats might be able to filibuster such a law and block it. But either way, Walker's entire trajectory as a national figure has established that Republicans are willing to get bolder about standing up for conservative convictions on labor law issues.