Marlon Peterson served 10 years in prison for his involvement in a serious crime nearly two decades ago. He’s now a social justice activist and recipient of multiple distinctions recognizing his leadership work with youth and gun control causes. He has a podcast, and is working on his first novel.

Too often, Peterson says, only the first fact about him matters. In a scathing op-ed for USA Today last month, Peterson wrote that after chaperoning some young people during the pro-gun-control March for Our Lives in March, he wanted to extend his stay in Washington DC by a couple of days. He tried booking an Airbnb, but failed to secure a reservation. Following a standard background check the platform performs on all US users, his conviction 16 years ago for attempted robbery, and first- and second-degree assault rendered him banned from Airbnb.

Whether people with criminal convictions on their record should be allowed to use a service that lets them rent members’ private homes is a complicated question, which Peterson acknowledges. Convincing renters or hosts to share a space with someone whose background check doesn’t return clean is a hard sell. But Peterson, as well as other criminal justice advocates, argues that banning people who have already been punished for their mistakes from participating in the modern economy is deeply unfair. Ex-offenders are deprived of many rights in the US, but there’s a growing movement to break barriers that prevent them from voting, getting employment, and housing.

“After years of healing and loving work, I am confronted, yet again, with the cruel reality that society makes people like me keep paying for mistakes far beyond our prison term,” he writes.

Airbnb’s policy on who is allowed on the platform is messy, and it’s not clear how exactly the company came up with its rules. Nick Shapiro, Airbnb’s global head of trust and risk management, said the company is reevaluating them.

Until pressed by Quartz, the “help” section of Airbnb’s website outlined some of the crimes that get you banned from the site, but did not specify any temporal restrictions, or go into detail (the site was updated with this information on Thursday). Other users would raise similar questions as Peterson on the platform’s chatroom, confused about the policies.

The website extensively describes Airbnb’s use of background checks, stipulating multiple times that users should not rely on these checks as sole indicators of a safe guest or host, since they can be spotty. Shapiro would not specify which companies Airbnb uses to conduct background checks, only saying they follow the Fair Credit Reporting Act guidelines.

Hosts have the right to ask a prospective guest for a government ID, which Airbnb verifies without showing it to the host. Hosts can refuse a booking “if you don’t feel right” about it.

In conversations with Quartz, via phone and email, the company clarified some of the details of its policy. The general rules, for both renters and hosts, are as follows:

The company does not do background checks globally. Outside the US, renters and hosts are checked against financial sanctions and terrorism watchlists.

It’s not clear how parole and probation figure into these policies. Shapiro said the two forms of supervision “are all part of our evolving thinking on this.”

The company used “the US federal sentencing guidelines to help us create this policy ranking the seriousness of crimes overlaid with the particulars of Airbnb (for example physical violence crime convictions are more problematic than drug offenses) to determine the removal timeline for each individual offense,” Shapiro said in an email. When the platform put the policy in place, it did it “knowing that in the US judicial system, unfortunately, people of minorities share too much of the burden in criminal convictions.” So, Shapiro said, the company tries to find “a balance,” disregarding less serious offenses.

Airbnb spokesperson Nick Papas said a range of experts, including “leaders from the civil rights community,” whom he wouldn’t identify, were consulted in the process. The company would not go into more detail as to how it came up with its policies.

The view from the other side

JoAnne Page, president of the Fortune Society, an organization that helps thousands of formerly incarcerated people re-enter society each year (and a previous employer of Peterson’s) said Airbnb’s current bans were “egregiously long.”

“Sentencing and punishment should only be the province of the judge, it should not be a function that is then repeated by a private business after the punishment set by the court has been completed,” she said in an email.

The Fortune Society is involved in a lawsuit against a New York landlord in which the organization claims that rejecting someone based on their criminal record is illegal because it is equivalent to racial discrimination. As part of the lawsuit, the group is looking at best practices in housing, which Page argues is an analogous field to Airbnb’s services.

While assessing whether a person is a safety risk, Page said, “individualized review,” or taking a close look at the context of a person’s life is crucial. In housing situations, Page said, ideally the landlord would first examine whether a person is a viable renter, based on indicators such as credit score, and history of paying rent. Only then do you look at whether someone poses a threat.

A good practice to establish the risk of violence—used by, for example, New Orleans’ housing authority—is to establish a “lookback period” of a certain number of years. If the crime occurred beforehand, it would not be relevant.

“What matters most in judging how safe a person is what they’ve been doing in the recent past,” she said. For example, a person convicted of murder several decades beforehand might be a perfectly safe tenant.

This, to a certain extent, is supported by research. Most criminals age out of violence before they hit mid-adulthood.

A notable exception here might be certain sex offenses, such as child molestation. But a blanket ban on people who are on sex offender registries is also misguided, Page said. The registries include legitimate criminals—abusers, molesters, pedophiles, rapists. But they also include teenagers who have sent each other sexual texts, 18-year-olds who have sex with partners barely younger than themselves, and people who have urinated in public.

A Silicon Valley cause du jour

The rise of the sharing economy has run into a widening push to stop denying the formerly incarcerated certain basic rights. The “Ban the Box” effort, which aims to look at job applicants without considering their conviction history, has been gaining steam in recent years. The debate gets complicated by the nature of the sharing economy, which by pairing private citizens in exchange of services, largely depends on trust. In the case of Airbnb, it confronts people directly, by coming into their homes.

But criminal justice reform is a popular topic in Silicon Valley, where most sharing economy companies have their headquarters, and the discussion is affecting their thinking.

Uber has been grappling with the issue as well. On the one hand, local laws regulating transportation services impose their own restrictions on hiring people with certain criminal offenses, and the company has had to pay fines for violating these rules. On the other, assaults by Uber drivers, and other similarly scary situations, are constantly in the news. This year, Uber introduced annual background checks for its drivers. But in 2016, the company also relaxed its rules on hiring drivers with minor convictions in California after the state re-classified some felonies as misdemeanors. The company’s cofounder and now former CEO Travis Kalanick even wrote an op-ed explaining the decision.

TaskRabbit, the company that matches people who need various handyman services with freelance workers, has a policy that resembles more closely the recommendations of Fortune Society’s Page. The company, which boasts 60,000 “vetted” workers on its website, conducts criminal background checks. ”If a previous criminal conviction is flagged as part of those checks, a member of our team will perform an individualized assessment of each instance,” a spokesperson told Quartz. “These case-by-case reviews take into account the totality of the information available, including the specifics of the conviction and how long ago it took place.”

A spokesperson for HomeAway, the parent company of several home rental companies like VRBO, and Airbnb competitor, said it conducts “certain background screenings on homeowners and take appropriate action when applicable, often including removing their property from our site,” but would not go into more detail about its policies, declining to answer what the company does for guests, for example.

For its part, Airbnb is trying to be careful about how it proceeds. Like Uber, it’s forced to consider multiple news stories that detail stories of wanted criminals staying in Airbnb apartments, or renters being hosted by convicted rapists, examples of which Shapiro sent to Quartz.

The company, valued at $31 billion in its last financing in July 2017, is reportedly preparing to go public in the next year, as it continues to face various pressures. Throughout its decade-long history Airbnb has had to battle with the hotel industry and cities over housing laws, and has been sued many times by local authorities and individuals—including for racial discrimination and for failing to warn a renter who said she was sexually assaulted by a host that he had previously been charged with battery. It has long been contending with charges of prejudice and perpetuating racial inequality.

Shapiro underlined that Airbnb was reviewing its current policies, admitting that “we don’t have a system in place where we could properly evaluate each person.” He said that establishing an appeal system in cases where “someone has clearly shown evidence of rehabilitation” was “worth discussing,” and that the company had been considering such a solution. Helping Airbnb with assessing its policies is civil rights law firm Relman, Dane and Colfax, which also represents the Fortune Society in its New York housing lawsuit.