Holder, speaking at a Washington event for law enforcement supportive of criminal justice reforms -- such as increasing mental health and drug treatment, federal support for community policing and expanding re-entry programs for prisoners -- said the current administration is making the "unwise" decision to move against the trend for reform and to roll back Obama-era Justice Department policies.
"I believe our country is at a crossroads," Holder said. "Will we return to the policies of the past?"
He said the path pursued by Attorney General Jeff Sessions, particularly his decision to direct prosecutors to push for toughest sentences, runs "the risk of igniting" a new drug war and does not effectively fight crime.
He said the policies of Sessions' Justice Department, which has called for tougher sentencing, scaled back programs aimed at examining police involved shootings, opened the door to increased civil asset forfeiture and more private prison contracts, were not truly based on evidence or made with public safety as the principle driver.
"They are ideologically motivated," Holder said, calling the moves, "disappointing, dispiriting and ultimately dangerous."
Holder's remarks from the National Press Club took place just ahead of Sessions' Capitol Hill testimony
, placing the former and current Justice Department chiefs on opposite sides of Washington and on opposite sides of the ongoing debate over mass incarceration, community-police relations and what effective law enforcement truly means.
Former Deputy Attorney General Sally Yates, who was acting attorney general in the early days of the Trump administration before President Donald Trump fired her, spoke at the event later Wednesday with a straightforward call for criminal justice reform, voicing particular concern "when it comes to our levels of incarceration."
"We cannot jail our way into safer communities," Yates said.
And she said if Trump and Sessions did not take the lead on reform, then law enforcement on the state and local level had the power and the duty to work for change.
"This is too important of an issue for us to turn into a political football," Yates said.
In an interview on CNN's "The Lead with Jake Tapper"
later on Wednesday, Holder said he had tried to be respectful of the new administration but that it has been "difficult to watch."
"It is difficult to do what I thought was good work, work that made the nation better, more fair, more just, and to see those policies being, you know, taken apart," Holder said.
The group that held the event, Law Enforcement Leaders to Reduce Crime & Incarceration, sent a letter to Trump and Sessions on Wednesday calling on the administration to join the reform movement.
"It is vital to public safety that momentum for reform continue," the letter said.
The group called for a raft of changes, including the passage of a sentencing reform bill backed by a bipartisan pair of senators.
Holder likewise ended his remarks with a call for Congress to seize the stalled trend for criminal justice reform at the federal level and push the Department of Justice to change its current course.
"Congress can reverse these actions," Holder said. "We must not squander this opportunity."