Michelle Alexander, the author of an acclaimed book on mass incarceration, said Wednesday that African American voters should not support Hillary Clinton because of policies that former president Bill Clinton enacted and she supported that were detrimental to black communities.

In an essay in The Nation, Alexander, the author of “The New Jim Crow: Mass Incarceration in the Age of Colorblindness,said that black voters have been “remarkably loyal to the Clintons for more than 25 years” and blacks appear to be supporting Hillary Clinton over Bernie Sanders now, despite his vow to take on Wall Street and tackle mass incarceration.

“What have the Clintons done to earn such devotion?” Alexander wrote in the essay, entitled ‘Why Hillary Clinton Doesn’t Deserve the Black Vote.’ “Did they take extreme political risks to defend the rights of African Americans? Did they courageously stand up to right-wing demagoguery about black communities? Did they help usher in a new era of hope and prosperity for neighborhoods devastated by deindustrialization, globalization, and the disappearance of work?

“No,” she wrote. “Quite the opposite.

Alexander’s essay comes as Clinton moves on from her defeat in the New Hampshire primary and into South Carolina, where there is a large number of black voters. Former Attorney General Eric H. Holder Jr. is featured in a Clinton commercial running in South Carolina that is meant to appeal to black voters.

“I’ve known her for almost 25 years,” Holder says in the 30-second Clinton ad. “This is a woman who’s fought her whole life for children, to protect civil rights, voting rights and today Hillary is pushing hard for tougher gun laws and police accountability. If you want to make sure Republicans don’t take us backward, help Hillary move us forward.”

But Alexander, an associate professor of law at Ohio State University, said that while the Clintons are “courting the black vote,” President Clinton “presided over the largest increase in federal and state prison inmates of any president in American history.” She points out that the former president supported the 100-to-1 sentencing disparity for crack versus powder cocaine, championed the idea of a federal “three strikes” law and signed a $30 billion crime bill that created dozens of new federal capital crimes and mandated life sentences for some three-time offenders.

Both Bill and Hillary Clinton have expressed regret over the crime bill. In July, the former president addressed the issue at the National Association for the Advancement of Colored People’s annual meeting in Philadelphia.

“I signed a bill that made the problem worse,” Clinton told the group. “And I want to admit it.

A few months earlier, Hillary Clinton told an audience at Columbia University in New York that it is time for a nationwide overhaul of what she called failed policing and prison strategies. While she did not mention her husband, many of those policies grew out of the crackdown on drug crimes and the harsh sentencing policies that took place before and when Bill Clinton was president.

“We need to restore balance to our criminal justice system,” Clinton told the audience in her April speech.

A Clinton spokesman did not immediately respond to a comment about the Alexander piece.

Alexander’s book is considered to be the Bible for many sentencing reform advocates, attorneys who have it on their shelves and inmates who have copies of it in their prison cells. Last fall, Facebook chief executive Mark Zuckerberg said the book inspired him to visit San Quentin State Prison with his wife. “The New Jim Crow” is cited constantly during the bipartisan efforts to overhaul the criminal justice system and reverse the nation’s costly and troubling mass incarceration of mostly people of color.