ON DECEMBER 23 , the day before Christmas Eve, the United States’ largest mall moved to shut down a potentially landmark Black Lives Matter demonstration before it even really began.

Management at the shopping center, Mall of America, located just outside Minneapolis, had stores lower their metal security gates about half an hour before the protest started, part of a “lockdown” that cleared shoppers from that wing of the mall. Only moments after Black Lives Matter organizers entered the mall’s east rotunda, the cousin of Jamar Clark, whose death at the hands of police was the center of the protest, was led away by a throng of police. Organizers directed demonstrators to exit the mall toward the light-rail station. As protesters walked out, the mall broadcast a looping announcement in a friendly Midwestern voice: “Mall of America is now going into lockdown. Seek shelter in the nearest store, and follow employee instructions.”

In an earlier victory, mall attorneys won restraining orders against three protest organizers, even as they lost a more ambitious bid to force Black Lives Matter Minneapolis to take down all mentions of the protest on social media and to declare the demonstration cancelled.

A year earlier, Black Lives Matter protesters were able to spend close to 90 minutes in the shopping center, chanting slogans and staging a “die in.” This December, Mall of America threw its massive security and legal resources behind stifling the Black Lives Matter protest. Although the activists still managed to have mall stores shuttered during the holiday shopping period, organizers redirected the protest to the airport (Black Lives Matter Minneapolis says this facility, not the mall, was its real target all along).

Mall of America’s ability to so zealously suppress the December 23 protest there highlights how, in a nation where more and more public life takes place in privatized spaces, the ability to exercise First Amendment rights has become increasingly contingent. From Zuccotti Park to Twitter, some of the last decade’s most iconic venues for dissent have been privately run. In cities like New York, privately owned public spaces have been proliferating for several decades, racing ahead of the case law that will ultimately decide their relationship to Constitutional rights. And legal experts expect social media to be a primary subject of First Amendment battles for decades to come.

“In the eyes of the law, those spaces for speech can be shut down and subject to arbitrary censorship in ways that the public square cannot,” said Teresa Nelson, legal director for the ACLU of Minnesota. “We either need to resolve to give up our First Amendment rights or get them to shift along with our changing technology.”

Legal arguments that free political speech should be allowed at malls center around the idea that the shopping center has replaced the town square as a place where opinions can be heard and exchanged. Besides an on-site police station, the Mall of America features an amusement park and a wedding chapel, and hosts morning walkers. The publicly funded light rail line was designed to draw residents and tourists to its doors; the mall is the line’s last stop.

In a statement, Mall of America said its ban on political protests is in place to protect guest and employee safety, adding, “We respect the rights of free speech and peaceful assembly. However, the courts have affirmed our right as private property owners to prohibit demonstrations on our property.”

Unfortunately for those seeking to exercise dissent, a 43-year-old Supreme Court ruling tilted the judicial playing field in favor of the people who own spaces like Mall of America, leaving civil liberties activists to seek stronger First Amendment protections on a case by case, and often state by state, basis.

Since the modern mall was born in Minnesota in 1956, its place as a new form of city center has been debated.

Southdale Mall, located in the Minneapolis suburb of Edina, was designed by Victor Gruen, a Jewish, Viennese, socialist refugee who’d come to the U.S. fleeing the Nazis, according to a 2004 New Yorker piece. Gruen’s mall was meant to actualize a utopian vision of a city’s downtown. Southdale was supposed to be the centerpiece of a 463-acre project that included a park, a lake, housing, schools, and doctors’ offices. The mall was organized around a central plaza, with a fishpond, caged birds, and a café, a prototype that was repeated as malls sprouted across the U.S.

Of course, the mall was also designed to draw consumers smoothly from store to store, keeping them buying even on cold days in Minnesota. Over the years that part of Gruen’s project was enhanced, while the community-oriented elements fell away, stripping the architect’s vision to its purely commercial elements.

A Supreme Court ruling a decade before Southdale’s construction would lay the groundwork for the idea of the mall as a legal bastion for political speech. In 1946, the U.S. Supreme Court ruled in Marsh v. Alabama that a Jehovah’s Witness had the right to hand out religious pamphlets in a company town owned by the Gulf Shipbuilding Corporation. The privately owned town, according to the court, functioned just like a municipality, and thus the First Amendment applied on its streets.

But a 1972 ruling pivoted the legal system away from the idea that the more a private entity welcomes in the public, the more speech protections it must offer. In Lloyd Corp., Ltd. v. Tanner, the Supreme Court decided that Vietnam War protesters in Portland, Oregon could not hand out literature on the interior of this “relatively new concept in shopping center design …sometimes referred to as the ‘Mall.’” The court said that the private nature of a business “does not change by virtue of being large or clustered with other stores in a modern shopping center.”

States, however, may still decide individually that malls in their jurisdiction should allow political speech. A handful of states, including California, New Jersey, Colorado, and Massachusetts, have compelled malls to do so, at least to some extent, but more than a dozen others, including Minnesota, have held that malls are private spaces free to prevent such speech.

At Mall of America, restrictions on political speech are accompanied by a significant degree of militarization. The shopping center is often framed as Minnesota’s biggest potential terrorism target, so security there bulges beyond what you’d see at a typical suburban mall. Besides having its own police unit on site, the retail destination has a K9 program and a “special operations plain clothes unit,” which focuses on “threat mitigation.” Former airport agents from Israel helped design the behavioral profiling techniques that have been used by the mall’s undercover security. Such techniques came under fire in 2011 after an NPR report described how security staff had interrogated several individuals for innocuous behavior. Last year, The Intercept revealed that a mall “intelligence analyst” had created a fake Facebook account to befriend and monitor Black Lives Matter protesters as they planned the 2014 Mall of America demonstration.

On December 23 the lines between private security and publicly funded police blurred. An intimidating array of cops from several area police departments stood alongside mall security guards to confront the protesters.

“We are really dedicated to being nonviolent and really committed to keeping everybody who comes out for Black Lives Matter safe,” organizer Miski Noor said. “They showed up in riot gear when you’ve got people here with their babies in strollers chanting and singing Christmas songs.”

Deputy Chief Mike Hartley of the police department in Bloomington, Minnesota, where the mall is located, said that the police were there to protect against groups beyond the protesters that might come to the event, citing an incident in November, where racist attackers shot and injured five Black Lives Matter Minneapolis protesters who had been demonstrating at a local police precinct headquarters. But Hartley asserted that it was the mall’s decision alone to shut down businesses.

From the mall rotunda, as the lockdown announcement rang, the protest spilled onto a light rail train headed toward the airport. Once there, some protesters streamed out and moved past police into a stairway between the train platform and the entrance to the airport. Police confronted another set of protesters at the airport doors, and at one terminal demonstrators blocked a road. Security checkpoints inside the airport were closed, flights delayed. Police and transit managers shut down the train between the airport and mall.

As it turns out, protestors had moved from one First Amendment gray zone to another. In 1992, the Supreme Court decided to allow a ban by the Port Authority in New York and New Jersey against solicitation, reasoning that Hare Krishnas and other groups asking for money could disrupt the flow of airport business, which runs on a tight schedule. Public transit rulings have followed a similar pattern; in general courts have held that free speech activities should not disrupt the flow of traffic. Even on city sidewalks, without a permit, police can block a protest if it impedes pedestrian traffic.

The ostensible pursuit of security at transportation hubs can also have the effect of limiting First Amendment activity. Since 9/11, cities have decreased public access to airport spaces, including by banning non-ticketholders from accessing gates. Now, cities like Washington D.C. and New York are limiting access even to check-in areas to prevent homeless people from seeking shelter (officials in both cities cited safety concerns).

Battles over physical space for speech at malls, airports, and on public transportation may soon be overshadowed by fights for speech in digital spaces.

Today, privately managed networks like Facebook and Twitter have taken the place of city squares as sites of political dialogue. These platforms, whose business is speech, have an incentive that the Mall of America does not have to allow free speech. Users don’t want a speech platform that they know has been sanitized.

But Twitter and Facebook are not public forums. Like malls, profits drive those platforms’ design and their tolerance for free speech extends only as far the aggregate demand of their users. And like malls and airports, social media platforms are under new pressure from anti-terrorism forces as organizations like ISIS and al Qaeda use them to recruit new militants.

How far Twitter and Facebook stray from their minimally censored beginnings is to be seen. Decades after the first mall was built, architect Gruen would disown the grown-up version of his invention. He was horrified by the urban sprawl malls had helped engender, appalled by the “land-wasting seas of parking.” In a 1978 speech in London he declared, “I refuse to pay alimony for those bastard developments.”

Top photo: Police queue up at the Minneapolis-St. Paul International airport Lightrail stop, where a number of Black Lives Matter protestors attempted to enter the airport on December 23, 2015 in Minneapolis, Minnesota.