The House Oversight Committee chairman, James Comer, and Congresswoman Marjorie Taylor Greene are in a race to the bottom — copying the Democrats’ use of sex crimes law and lurid charges to smear political opponents. 

The pair have written to the Department of Justice asking if it is “upholding the rights of victims who were sexually exploited by Robert Hunter Biden.” Their query is referring to Mr. Biden’s admitted use of prostitutes, which Ms. Greene has previously argued could be a violation of a 1910 law known as the Mann Act.

The Mann Act makes it a felony to transport a woman across state lines “for the purpose of prostitution or debauchery, or for any other immoral purpose.” Originally known as the White Slave Traffic Act of 1910, the law is more recently known as the Mann Act, after its sponsor, Congressman James Robert Mann of Illinois.

“Considering DOJ’s public campaign purporting its commitment to prosecuting human trafficking and other sexual exploitation crimes, DOJ should respond to Congressional requests related to this issue in a timely and thorough manner,” Mr. Comer and Ms. Greene wrote. They suggest that the prostitutes with whom Mr. Biden allegedly consorted could be entitled to money from a “Crime Victims Fund.”

Ms. Greene, one of the House’s most high-profile conservatives, wants to know if Mr. Biden traveled either across state lines or internationally with sex workers, which would violate the Mann Act. Ms. Greene has not offered any evidence that Hunter Biden traveled across state or international borders with prostitutes. 

The Mann Act served as the same basis for the recent investigation by the Department of Justice into one of Ms. Greene’s conservative colleagues, Congressman Matt Gaetz, who is among President Trump’s strongest supporters in the House. No charges were filed against Mr. Gaetz after a years-long investigation of his alleged dalliances with a 17-year-old woman, which Mr. Gaetz has denied.

Ms. Greene and Mr. Comer had initially asked DOJ to investigate the first son in July, but nothing came of it. “DOJ’s decision to ignore the Committee’s request runs afoul of its own policies in the Justice Manual,” they wrote to the National Human Trafficking Coordinator at DOJ, Hilary Axam, and the director of the Office of Victims of Crime, Kristina Rose.

“The agency’s policies clearly state, ‘it is important that the Department provide timely responses to congressional inquiries,’” the lawmakers continued. “Unfortunately, DOJ’s leadership continues to apply unwritten exceptions to its own rules and policies when the Bidens are involved.”

Mr. Biden has acknowledged paying for sex during his years of severe alcohol and drug addiction; he says he is now sober. Ms. Greene has cited the contents of Mr. Biden’s infamous laptop, which contains obscene selfies and videos with women who appear to be prostitutes, as evidence of his violating the Mann Act. The law was amended in the 1970s and 1980s to only include the transportation of sex workers and minors as felony violations. 

The Mann Act has been deployed just in the last few years as a way of prosecuting men for sex offenses with minors. Singer R. Kelly was convicted of violating the Mann Act, as well as the Racketeering Influenced and Corrupt Organizations Act — crimes for which he ultimately received a 30-year prison term. 

The girlfriend of the late financier Jeffrey Epstein, Ghislaine Maxwell, was sentenced to 20 years in prison after a jury found she had violated the Mann Act, among other crimes, for coordinating his use of teenagers for massages and sexual encounters in different states and countries.

Defense attorneys have long argued that prosecutors are abusing the original intent of the Mann Act by using it to prosecute individual sex crimes that don’t involve running a large-scale prostitution enterprise with multiple clients.

Prosecutors’ novel use of the law mirrors how District Attorney Fani Willis in Fulton County, Georgia, has used the RICO Act, which was signed by President Nixon to go after the Mafia, to prosecute Atlanta teachers, rappers, and, most recently, President Trump and his aides for “conspiring.”

In the case of Mr. Trump, the Manhattan district attorney, Alvin Bragg, has used election law to prosecute the former president regarding his alleged affair with an adult film star, Stormy Daniels. The writer E. Jean Carroll recently took advantage of New York’s new Adult Survivors Act, which allows a one-year amnesty for victims of sex assault to sue their attackers long after the statute of limitations has passed, to sue Mr. Trump for an assault she claims took place in the 1990s.

A spokesman for Ms. Greene did not immediately respond to a request for comment. Her accusation that Mr. Biden violated the Mann Act first came during a high-profile hearing before the Oversight Committee that included testimony from two Internal Revenue Service whistleblowers who claimed that the first son received “preferential treatment” from the DOJ during a yearslong criminal investigation. 

During that hearing, Ms. Greene held up large photographs on posterboard taken from Mr. Biden’s laptop, which included obscene images of the first son and women who Ms. Greene said were prostitutes. Ms. Greene also showed evidence that Mr. Biden paid for a cross-country flight for a woman with whom he was having an affair, but there is no evidence that she herself was a sex worker.  

In an aggressive public relations turn, Mr. Biden’s legal team later filed an ethics complaint against Ms. Greene for displaying the lewd photos, saying she “has lowered herself, and by extension the entire House of Representatives, to a new level of abhorrent behavior that blatantly violates House Ethics rules and standards of official conduct.”