In August, delegates from Amnesty International voted to approve a policy supporting the decriminalization of prostitution. The decision touched off a fierce debate among feminists, sex workers and the wider public about whether decriminalization or prohibition of prostitution contributes more to trafficking and sexual exploitation.

A letter signed by Meryl Streep, Lena Dunham, Anne Hathaway, Lisa Kudrow and Emma Thompson — all well-to-do actresses whose experience is limited to, at most, playing a prostitute in a movie — expressed deep dissatisfaction with Amnesty’s “proposal to adopt a policy that calls for the decriminalization of pimps, brothel owners and buyers of sex” and recommended harsher crackdowns on johns instead. Perhaps celebrities like Streep and Dunham could listen more closely to the perspectives of sex workers themselves — many of whom favor decriminalization and hold more complicated views of the agents who help prostitutes sell sex.

A letter drafted by the International Committee on the Rights of Sex Workers in Europe and signed by 180 advocacy organizations, including the English Collective of Prostitutes, the Association of Hungarian Sex Workers and the Sex Work Association of Jamaica, among others, claimed Amnesty’s new campaign would make “a significant contribution to promoting sex workers’ human rights and protecting them from discrimination and violence.”

Of course, there are plenty of people who have experience with sex work and oppose decriminalization. Rachel Lloyd, founder of Girls Educational and Mentoring Services and a former sex worker herself, attacked legal prostitution in a recent New York Times opinion piece and recalled working underage in Germany’s legal prostitution scene.

Indeed, even when legal, the sex industry is rife with exploitation and substance abuse. Lloyd pointed to the estimated 70 to 90 percent of women and girls who are sexually abused prior to working as prostitutes as evidence of the immorality of legal sex work, and accounts abound of the culture of copious drug use and physical and financial dependence that entraps many sex workers.

The state of sex work is obviously problematic, but the question is whether decriminalization would make it better. Research into decriminalization suggests it would. A 2012 United Nations study found that the decriminalization of sex work in New Zealand in 2003 expanded “access to H.I.V. and sexual health services and is associated with very high condom use rates.”

The logic of decriminalizing sex work is easy to grasp: A legal market for sex enables prostitutes to shop their services around to secure better wages and working conditions. It also allows for regulation to better protect sex workers and combat the spread of STDs — a benefit evident in the New Zealand study.

Decriminalization yields benefits to the wider public as well. In 1980, Rhode Island legislators mistakenly removed language defining prostitution as a crime, effectively decriminalizing sex work and offering researchers a perfect natural experiment. The results were remarkable: The number of gonorrhea cases and rapes reported statewide fell 39 percent and 31 percent, respectively, according to a study by the National Bureau of Economic Research.

Conversely, criminalizing either the selling or buying of sex flushes sex workers into a seedy criminal underworld where, absent any regulations or the protection of law enforcement, prostitutes remain extremely vulnerable to disease and abuse.

One needn’t be comfortable with personal histories of prostitutes or the conditions in which they work to favor the spread of decriminalization. If a more legal market makes sex workers safer, it’s a major improvement on the status quo.