Back in October the Supreme Court agreed to hear a case called Glacier Northwest Inc v International Brotherhood of Teamsters Local Union No. 174. Oral arguments will be heard in the case tomorrow and some union supporters worry it could be used to undermine the right to strike. Here’s how Slate reported it at the time:

…the court earlier this month agreed to hear a case asking whether workers should have to face crippling lawsuits if they exercise their right to strike: Glacier Northwest Inc. v. International Brotherhood of Teamsters Local Union No. 174. Given the court majority’s recent history of extreme hostility to workers’ exercise of collective power, this development is seriously concerning. Everyone who cares about workers’ rights should be paying close attention.

Glacier is a Washington corporation that sells and delivers concrete, which hardens quickly if it is not constantly mixed. After the prior collective bargaining agreement between the company and its workers expired, and amid negotiations for a new contract, more than 40 Glacier workers went on strike.

When the strike began, all the striking drivers left their trucks running so the cement in them wouldn’t dry out; turning off the ignition would not only have rendered the cement unusable, but also permanently damaged the trucks.

The company managed to empty the cement out of the trucks, and there was no harm to the vehicles or premises. But the company had made no contingency plans for back-up staffing, so it lost money because it had to dispose of the cement itself. Glacier sued the union in state court for damages based on the loss of the cement.

Politico has a story up today saying that labor unions are “fearful that the conservative majority could undercut the appeal for workers to strike and sap authority from the National Labor Relations Board.”

At issue is whether employers can sue unions accused of destroying property as part of a labor dispute in state court, or whether such a lawsuit is preempted by federal labor law…

Washington’s Supreme Court ruled that Glacier Northwest’s civil lawsuit should be dismissed because the legality of the strike falls under the NLRB (which later sided with the union). In court filings, businesses and conservative legal groups argue these types of lawsuits are not preempted by federal law and should be allowed to proceed.

The best explanation I’ve seen of what’s really at stake in this case comes from the Federalist Society which spells out the fine line that separates when companies can file a lawsuit over a strike and when they can’t.

The heart of the case is preemption doctrine under the National Labor Relations Act (NLRA). Though the NLRA says nothing about preemption, courts have interpreted it to have one of the broadest preemptive scopes in federal jurisprudence. The reason comes from history. In the early twentieth century, labor disputes and work stoppages were much more common than they are today. They were also much more disruptive. They often ballooned to envelop whole industries and were marred with violence. For example, during the infamous Pullman Railroad Strike, interstate rail shipments were shut down for months, and as many as thirty strikers were killed by federal troops. Other strikes caused similar chaos.

The NLRA was meant to calm the situation. Instead of leaving employers and unions to resort to self-help, it pulled them into a nationwide regulatory regime. That regime encouraged them to resolve their differences through collective bargaining. And it funneled their complaints through a new federal agency, the National Labor Relations Board. The Board, not courts, was supposed to craft and enforce labor policy for the whole country.

Given that design, courts reasoned that Congress must have wanted to prevent states from contradicting the Board with different local rules. So they cast a wide preemptive net. In particular, they barred states from regulating any conduct “arguably” protected by federal law. And they forbade states from offering new or additional remedies for conduct “arguably” forbidden.

So that’s what happened in this case. Glacier sued in state court and eventually lost at the state Supreme Court on the grounds that this was a matter for the NLRB to handle. But then the Supreme Court took up the case which means they are looking to reverse the Supreme Court and issue a different ruling in this case. But according to the Federalist Society, that doesn’t mean the Court is about to gut the NLRB.

In fact, the Court granted cert on a narrow question: whether the NLRA preempts a claim under state law for intentional destruction of property. The “intentional” part is important. The case is not about economic loss generally. It’s not about lost orders, inconvenience, or spoiled goods. Instead, it’s about only intentional and willful destruction. It presents a simple, clean issue: does federal law preempt property-destruction suits simply because they’re connected with a strike?

And unusually for a Supreme Court case, the answer is relatively clear—at least according to the Court’s own caselaw. Since the 1930s, the Court has held that intentional property destruction falls outside the NLRA’s protection. And since at least the 1970s, it has held that property-related torts also qualify for the “local feeling” exception. Like other intentional torts, property-related torts implicate deep-seated local interests. So it would be inappropriate to preempt them, even when they involve arguably protected conduct.

In Glacier, the state courts put their own gloss on that precedent. They required the company to produce additional evidence—either of violence or “outrageous conduct.” But that gloss wasn’t only new; it also clashed with the Court’s prior decisions. In the past, the Court has allowed property claims to go forward even when the underlying dispute was peaceful. For example, in Sears, Roebuck & Co. v. San Diego County District Council of Carpenters, a union set up a picket line on the employer’s property. The employer then sued for trespass. And even though the picketing was peaceful—and arguably protected by federal law—the Court allowed the suit.

In this case, the argument appears to come down to whether or not the union timed the strike to intentionally waste multiple loads of concrete. This description comes from the Washington State Supreme Court decision:

On August 11, 2017, Glacier had a number of scheduled deliveries. Around7:00 a.m. that morning, drivers at Glacier’s Seattle, Kenmore, and Snoqualmie facilities engaged in what Glacier describes as a “sudden cessation of work.” Clerk’s Papers (CP) at 6. Glacier alleges this work stoppage occurred with truck drivers at every stage of the delivery process, including trucks waiting to be loaded, being initially loaded with concrete, driving en route to delivery sites, and already at sites delivering the concrete. A declaration of Adam Doyle, a dispatch coordinator, stated that drivers were scheduled to start work that day between 2:00 a.m. and 7:00 a.m. After learning of the strike, Doyle announced over the radio that “‘I’ve just been informed to advise you that we are obligated to finish any job that we have started.’” CP at 208. Doyle further explained the normal process for drivers who return their trucks after making a concrete delivery, stating that the driver “offloads his leftover concrete into a reclaimer or into an ecology block form. He then rinses out his drum, and he gets back in line for his next load.” CP at 208. But on that day, Doyle explained that drivers all brought their trucks back between 7:00 a.m. and 7:45 a.m., and he noted that many of the trucks were left with partial or full loads of concrete. Justin Denison, the ready-mix concrete manager for all facilities in Washington, was present at the Duwamish facility when the strike occurred. He stated that at least 16 drivers returned to the site with trucks fully loaded with concrete. While 7 of these drivers gave Glacier notice of the return of the trucks, 9 drivers left trucks without notice to Glacier.

Glacier alleges Local 174 had coordinated with truck drivers to purposely time the strike when concrete was being batched and delivered in order to cause destruction of the concrete. Glacier further alleges its drivers and Local 174 were fully aware that the concrete was perishable. As a result, Glacier had to take mitigation measures to dispose of the batched concrete on site through “constructed bunkers” and to clean out the trucks to prevent any damage to the trucks or to its plant, equipment, and wastewater system.

The drivers had the right to strike but by ordering the strike to begin after trucks had been loaded and sent out the union arguably made a decision to intentionally destroy those loads of concrete. Had they simply announced the strike the night before, Glacier wouldn’t have loaded all those trucks and wouldn’t have had to dump and dispose of dozens of yards of wasted concrete (a full truck holds about 10 yards) when the trucks all returned to the plant full.

Tomorrow we’ll get our first indication of how the majority of the Justices feel about this case or whether they have anything more in mind than the narrow question of whether the company can sue for destruction of property under these circumstances.