The issue arose in a case involving a grocery store in Sacramento, Calif., owned by the Ralphs grocery chain. 

The store’s workers are not unionized. Shortly after it opened in 2007, members of the United Food and Commercial Workers Union Local 8 began picketing the business five days a week, eight hours a day. 

The group of four to eight union members picketed at the front entrance to the store on private property and in the privately owned parking lot. 

Store managers complained that the protests were confrontational and designed to undercut the store’s commercial operations by attempting to encourage customers to boycott the non-union business. 

The company asked police to remove the protesters from its property. The police said it needed a court order. 

Ralphs filed suit against the union in 2008, seeking a court order and injunction to block the labor group from picketing on its private property. 

The store’s lawyers challenged the constitutionality of two provisions of California law that place restrictions on the authority of state courts to issue injunctions concerning a labor dispute. They are state versions of a 1932 federal law that barred the federal courts from becoming involved in efforts to break an ongoing strike. 

The law established that unions have a right to peacefully publicize a labor dispute and that the courts may not interfere with that right. 

Lawyers for the California union argued that the state provisions are constitutional and deserve to be upheld. 

A California judge questioned the constitutionality of the two provisions, but ultimately upheld them and declined to issue an injunction against the union based on existing legal precedent in California. A state appeals court, however, reversed that decision. The appeals court overturned the earlier precedent and declared both laws unconstitutional. 

The case went to the California Supreme Court. The state high court reversed the appeals court and declared that the two state laws at issue did not violate free speech and equal protection guarantees in the US Constitution.

Urging the US Supreme Court to take up the case, lawyers for Ralphs said the California provisions give those engaged in labor-related speech a “free pass to trespass on private property by closing the court-house doors to the property owner.” 

“If the content of the protester’s speech had been about any other topic – had they been proselytizing, campaigning, protesting military action, or requesting charitable donations – the protesters would have been trespassers, and Ralphs could have obtained injunctive relief compelling them to stay off Ralphs’ property,” wrote Deanne Maynard in a brief to the high court on behalf of grocery-store chain. 

“But because the content of the protesters’ speech was about labor issues, the Supreme Court of California held that the Union representatives could not be ejected from Ralphs’ private property by Ralphs or by any court,” Ms. Maynard wrote. 

There is no evidence that union picketers impeded or harassed customers at the store, San Francisco lawyer Steven Stemerman wrote in his brief on behalf of the union. 

He warned the justices about the potential consequences of embracing the grocery chain’s view of the law. 

“Accepting Ralphs’ theory would have radical implications,” Mr. Stemerman said. Similar laws, both at the federal level and in many states, would face challenges and be subject to the highest level of judicial scrutiny, he said. 

He said that the California laws do not abridge anyone’s free speech rights and thus cannot violate the First Amendment.

The case was Ralphs Grocery Company v. United Food and Commercial Workers Union Local 8 (12-1162).