Everyone knows that it’s illegal for a hotel such as a Marriott or a Hilton to refuse you a room because of your race. But what about someone who temporarily rents out their own apartment on Airbnb? May he refuse to rent to someone of a particular race? If two people want to rent out the same room, may the landlord prefer a person of one race over another? Moreover, what if the preference is subconscious and a landlord doesn’t even realise she is discriminating? Although Airbnb offers more rooms than most leading hotel chains, the answers to these questions are far from clear. Questions such as these are increasingly important in the “sharing economy” in which businesses connect people offering goods and services with other people who want to pay for them. Some businesses, such as Airbnb and VRBO, allow individuals to rent out rooms in their homes, while the likes of Lyft and Uber allow people to use their personal cars to transport strangers in their city.

In some instances, sharing economy businesses arguably reduce discrimination. For example, some black passengers have noted that Uber is an improvement over the perennial difficulty in hailing a cab. In 2014, one of us expressed concern about the unique ways in which race discrimination can affect the sharing economy. Since then, the sharing economy has grown exponentially, and a recent National Public Radio story highlighted new evidence suggesting that race discrimination affects Airbnb rentals.

One study, conducted by Benjamin Edelman, Michael Luca and Dan Svirsky at Harvard Business School, reveals that people whose names are perceived to signal black identity find it approximately 16 per cent more difficult than their white counterparts to rent rooms on Airbnb. Particularly troubling is the finding that in some instances, Airbnb users would rather allow their property to remain vacant than rent to a black-identified person.

The story clearly struck a nerve: Twitter hashtag #AirbnbWhileBlack, coined by NPR reporter Shankar Vendantam, went viral on Friday, and perusing it reveals dozens of troubling accounts of black people trying and failing to rent sharing economy accommodations.

In our article “The New Public Accommodations,” forthcoming in the Georgetown Law Journal, we examine possible legal remedies for race discrimination by participants in the sharing economy, such as Airbnb hosts and Uber drivers. Race discrimination by sharing economy participants requires us to consider how the law should take account of subtle or even subconscious bias that results in race discrimination. Moreover, discrimination in the sharing economy adds a new twist: how should the law respond when, for example, the discriminator is not a desk clerk at a hotel but rather a private property owner renting out her own home? The sharing economy blurs the line between public and private in a way that is very popular, but that raises a host of questions that don’t have easy answers.

How may victims of racial discrimination in the sharing economy seek justice, and what would that mean for civil rights law? Title II of the Civil Rights Act of 1964 explicitly prohibits discrimination in places of “public accommodation” such as hotels, restaurants, movie theatres and sports arenas.

There is an intuitive argument that Airbnb rentals should qualify as places of public accommodation. After all, they are displacing hotels and serve exactly the same function: providing travellers a place to stay when they are away from home.

However, Title II includes an exception for someone renting fewer than five rooms in their own home. This language could be read to exempt Airbnb owners who live in the properties they rent out. But that may only be true if we see each individual Airbnb owner as an individual establishment. The statute could also reasonably be read to treat all of Airbnb as one big public accommodation that provides, without a doubt, more than five rooms. That interpretation may well mean that Airbnb is in violation of Title II.

Another possibility is the federal civil rights statute 42 USC § 1981, which prohibits race discrimination in contracting. Refusing to rent to a person because of their race is a textbook example of discrimination in contracting. But here we run into a problem of proof. Courts have held that section 1981 requires the plaintiff to show not only that she was treated differently because of her race, but also that the defendant intended to treat her differently. In an era of subconscious bias communicated through the impersonal filter of the internet, intentional discrimination can be nearly impossible to prove, particularly in a one-time interaction.

Moreover, sharing economy businesses themselves may be able to avoid liability by arguing they are merely passive participants who offer a software platform that simply connects willing participants. In this case, Airbnb could claim that it does not make any decisions on behalf of participants, let alone intentionally discriminatory ones.

When it comes to Airbnb, another potential means of redress in instances of discrimination is the Fair Housing Act. Like Title II, it prohibits discrimination in rentals, but courts have held that it applies to real estate brokers, perhaps a better analogy for Airbnb than a hotel. Moreover, unlike section 1981, the Supreme Court has held that there is no requirement of discriminatory intent. Even if the Fair Housing Act applies to Airbnb, however, many other sharing economy businesses such as Uber, Lyft, TaskRabbit and Postmates do not involve housing, so discrimination by such businesses would remain unaddressed.

How existing civil rights law applies to our new sharing economy is far from clear.

And as we discuss in our research, there may be other obstacles to legal recourse as well. For example, the Communications Decency Act limits website operators’ responsibility for some kinds of illegal behaviour by users. In the end, it may be that our existing civil rights laws simply need updating — either quickly, through legislative action, or incrementally, through court decisions. But in the meantime, the experiences of people of colour make clear that Airbnb rental is just another way in which our society is not yet colour-blind.

• Aaron Belzer is an appellate law clerk and was formerly an associate at Rathod Mohamedbhai in Denver. Nancy Leong is an associate professor at the University of Denver Sturm College of Law