As someone who has spent almost two decades working to end the drug war, I have very specific concerns about how Alabama Sen. Jeff Sessions, Donald Trump's selection for U.S. attorney general, could use existing policies to target already vulnerable communities.

Sessions' record shows he's likely to escalate the war on drugs by undermining civil rights, stifling state-level marijuana reforms that have drastically reduced arrests in communities of color and rolling back much of the progress in policing and criminal justice reform made by the Obama administration.

The last time Sessions faced a confirmation vote, in 1986, his nomination was voted down by the Republican-controlled Senate Judiciary Committee after they were confronted by Sessions' extensive history of racist comments and actions. A black colleague testified that Sessions referred to him as "boy." Sessions referred to the NAACP and other civil rights organizations as un-American groups that "forced civil rights down the throats of people." He was accused of using his authority as a U.S. attorney to disrupt and prosecute civil rights activists who were registering African-Americans to vote. He even reportedly said he thought the KKK was "OK" until he found out its members smoked pot.

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Some people say this is old news. Not me. Sessions has been one of the Senate's most obstructionist and harmful voices on issues affecting immigrants, Muslims, African-Americans, Latinos, women and the LGBTQ community. He can't be trusted to be America's top law enforcement official.

When it comes to drug policy reform, Senator Sessions has nearly single-handedly blocked bipartisan sentencing reform and has been unduly critical of the Justice Department's use of consent decrees that force local police departments to address police brutality, racial profiling and other civil rights issues. Moreover, he supports civil asset forfeiture, the process by which police can take people's money and property and keep it for themselves without having to convict anyone of a crime. He opposes granting formerly incarcerated individuals the right to vote. (Felony disenfranchisement laws have deprived millions of the right to vote, including 30 percent of black men in the Deep South.)

Sessions recently said that "good people don't smoke marijuana" and has attacked the Obama administration for respecting state marijuana laws. If appointed, he could undo important changes made by Obama's Justice Department by expanding the use of mandatory minimum sentencing and raiding marijuana dispensaries in states where it's legal.

In Sessions' hands, the war on drugs could be used as a weapon to spy on, investigate, incarcerate and deport immigrants, Muslims and other targeted groups. Already, President-elect Trump has said he will try to deport any immigrant who commits any kind of criminal offense, no matter how minor, including drug offenses.

For noncitizens, including legal permanent residents, most drug law violations can trigger automatic detention and deportation, often without the possibility of return. Every year since 2008, roughly 40,000 people have been deported from the U.S. for drug law violations – many for simple marijuana possession. And that was without an attorney general who was openly hostile to immigrants and people who use drugs.

The war on drugs has a long history of being a cover for racial injustice. It's no coincidence that it was launched right after the civil rights movement made major gains. In Nixon's words (paraphrased by one of his staffers), "the whole problem is really the blacks, the key is to devise a system that recognizes this while not appearing to."

Once charged with a drug offense, people can be legally discriminated against in housing and employment, and denied student loans and public assistance. If their drug law violation was a felony, they can even be denied the right to vote – in some states for life.