(CNN) Attorney General Jeff Sessions has a new directive for federal prosecutors across the country: charge suspects with the most serious offense you can prove.

Friday's announcement follows a line of several other significant departures from Obama-era domestic policies at the Justice Department, but this decision crystalized Sessions' position in the criminal justice realm.

"Charging and sentencing recommendations are bedrock responsibilities of any prosecutor and I trust our prosecutors in the field to make good judgment," Sessions said Friday at a news conference in Washington. "They deserve to be un-handcuffed and not micromanaged from Washington."

In a brief one-and-a-half-page memo , Sessions outlined his new instructions for charging decisions in federal cases, saying that his new first principle is "that prosecutors should charge and pursue the most serious, readily provable offense."

"The most serious offenses are those that carry the most substantial guidelines sentence, including mandatory minimum sentences," Sessions later added.

Longtime Obama administration Attorney General Eric Holder blasted Sessions' "unwise and ill-informed" move, claiming the decision would "take this nation back."

"The policy announced today is not tough on crime. It is dumb on crime. It is an ideologically motivated, cookie-cutter approach that has only been proven to generate unfairly long sentences that are often applied indiscriminately and do little to achieve long-term public safety," Holder said in a statement.

He added, "this administration reveals its lack of faith in their judgment and integrity."

Sessions, however, called the move "simply the right and moral thing to do" at Friday's news conference. And in an apparent reference to Obama administration policies, he said "It is important to note that unlike previous charging memoranda, I have given our prosecutors discretion to avoid sentences that would result in an injustice."

While the federal sentencing guidelines are advisory -- and take into account everything from a defendant's criminal history to cooperation with authorities -- some judges have felt handcuffed by mandatory minimums, which provide a statutory sentencing minimum of months below which the judge cannot depart.

Sessions also formally withdrew a signature part of Attorney General Eric Holder's "Smart on Crime" initiative, which sought to target the most serious crimes and reduce the number of defendants charged with non-violent drug offenses that would otherwise trigger mandatory minimum sentences.

"We must ensure that our most severe mandatory minimum penalties are reserved for serious, high-level, or violent drug traffickers," Holder wrote in a 2013 memo. "In some cases, mandatory minimum and recidivist enhancements statutes have resulted in unduly harsh sentences and perceived or actual disparities that do not reflect our Principles of Federal Prosecution."

As a result, during the Obama era, federal prosecutors were instructed not to charge someone for a drug crime that would trigger a mandatory minimum sentence if certain specific factors were met: (a) the relevant conduct didn't involve death, violence, a threat of violence or possession of a weapon; (b) the defendant wasn't an organizer, leader or manager of others within a criminal organization; (c) there were no ties to large-scale drug trafficking operations; and (d) the defendant didn't have a "significant" criminal history (i.e., prior convictions).

All of those charging factors are now gone under Sessions' reign and not surprising, as he has previously telegraphed his desire to prosecute more federal cases generally.

The effects of Friday's decision are likely to be felt most immediately in the narcotics context, where federal mandatory minimums established by Congress can be harsh for even first-time offenders because the sentences are dictated based on drug type and quantity.

CBC says directive 'discriminatory'

The move swiftly drew outrage from progressives. Congressional Black Caucus chairman Cedric Richmond called Sessions' newest directive "discriminatory" and said the policy previously "destroyed" families.

"Our biggest concerns about Attorney General Sessions are becoming reality. Yesterday's action doubles down on a policy that we know was ineffective and discriminatory," the Louisiana Democrat said Friday. "In the name of helping communities, this policy destroyed many of them, including the families that live there."

"It is widely known that every $1 we spend on mass incarceration makes the country less safe, but Attorney General Sessions has not learned this lesson and is determined to continue the war on drugs with extremely brutal force," he said.

The move also was harshly criticized by the New York University School of Law Brennan Center for Justice, a nonpartisan law and policy institute focused on democracy and justice.

"The Trump administration is returning to archaic and deeply-flawed policies," Inimai Chettiar, the center's program director, said Friday. "Sessions is leaving little to no room for prosecutors to use their judgment and determine what criminal charges best fit the crime."

"That approach is what led to this mess of mass incarceration," she added. "It exploded the prison population, didn't help public safety, and cost taxpayers billions in enforcement and incarceration costs."

Sherrilyn Ifill, NAACP Legal Defense and Educational Fund president, said Sessions' move will disproportionately impact black Americans.

"When President Trump asked black Americans what we have to lose by electing him, the answer is all the gains we've made in advancing justice and fairness," she said.

The American Civil Liberties Union said Sessions' move would return the government to failed policies and could prompt long mandatory minimum sentences.

"Jeff Sessions is pushing federal prosecutors to reverse progress and repeat a failed experiment -- the War on Drugs -- that has devastated the lives and rights of millions of Americans, ripping apart families and communities and setting millions, particularly black people and other people of color, on a vicious cycle of incarceration," said Udi Ofer, director of the ACLU's Campaign for Smart Justice.

Sen. Dick Durbin, an Illinois Democrat, said the policy shift will raise prison costs, undermine "public safety priorities" and "flies in the face of the growing bipartisan consensus that we need to reduce -- not increase -- the length of prison sentences for nonviolent drug offenders."

And Sen. Kamala Harris, a former California attorney general, said Sessions wants to revive the "war on drugs."

"That 'war' treated drugs, addiction, and substance abuse as a crime instead of as a public health issue," Harris told CNN.

"Undoing the great work that Attorney General Eric Holder did on sentencing reform, specifically around mandatory minimums, is wrong," the Democratic lawmaker added. "Jeff Sessions wants to turn back the clock on the progress we've made, and we're going to have to fight and speak out against it."