Sean “Diddy” Combs is set to be sentenced Friday for violating the federal Mann Act, an anti-prostitution law with a century-old history.

Although he was acquitted of sex trafficking and racketeering charges, Combs was convicted in July of flying people around the country, including his girlfriends and male sex workers, to engage in paid sexual encounters.

The Mann Act makes it illegal to transport someone across state lines for the purpose of prostitution or other illegal sex acts.

Over the years, the law has been used to prosecute R&B superstar R. Kelly, Jeffrey Epstein companion Ghislaine Maxwell, musician Chuck Berry and, more than a century ago, boxer Jack Johnson.

Its broad wording and a subsequent Supreme Court interpretation once allowed prosecutors to bring cases against interracial couples, and eventually many others in consensual relationships, according to Cornell Law School's Legal Information Institute.

The law was amended in the 1980s and today a lot of Mann Act prosecutions involve people accused of taking children across state lines for sexual purposes.

Here's what to know about the law.

In 1910, Congress passed the bill, which was named after Republican U.S. Rep. James Robert Mann of Illinois.

It’s also known as the “White-Slave Traffic Act” of 1910.

Combs was convicted of counts involving two former girlfriends: the R&B singer Cassie and a woman who testified under the pseudonym Jane.

Both women said at trial that Combs had pressured them into degrading sex marathons with strangers, who were paid for the sexual performances. Jane said she was once beaten by Combs for declining to participate. Cassie said that when she tried to walk out of one such event, Combs beat her and dragged her down a hotel hallway.

Combs was acquitted of sex trafficking and racketeering charges but convicted of transporting people to engage in prostitution.

The 1910 law originally prohibited the interstate or foreign transport of “any woman or girl for the purpose of prostitution or debauchery, or for any other immoral purpose.” It followed a 1907 congressionally appointed commission to look into the issue of immigrant sex workers, with the view that a girl would only enter prostitution if drugged or held captive, according to Cornell University's Legal Information Institute.

The law was used to secure a conviction against Jack Johnson, who became the first Black boxer to win a world heavyweight title in 1910. Johnson was convicted in 1913 by an all-white jury for traveling with his white girlfriend, who worked as a sex worker, in violation of the Mann Act.

President Donald Trump posthumously pardoned Johnson in 2018, saying Johnson had served 10 months in prison “for what many view as a racially motivated injustice.”

In a 1917 Supreme Court case, the justices ruled that “illicit fornication,” even when consensual, amounted to an "immoral purpose,” according to Cornell’s Legal Information Institute.

A 1986 update made the law gender-neutral and effectively ended the act’s role in trying to legislate morality by changing “debauchery” and “immoral purpose” to “any sexual activity for which any person can be charged with a criminal offense.”

The act received additional amendments in 1978 and 1994 to address issues of sexual exploitation of children.

Prosecutors have asked the judge to sentence Combs to more than 11 years in prison. Combs' lawyers have said he should be sentenced to no more than a year, arguing that testimony during the trial about alleged violent acts against women and others wasn't part of the conviction.