The Justice Department on Tuesday revoked a Trump-era memo that established a “zero tolerance” enforcement policy for migrants crossing the US-Mexico border illegally, which resulted in thousands of family separations, Associated Press reported.

Acting Attorney General Monty Wilkinson issued a new memo to federal prosecutors across the country, saying the department would return to its longstanding previous policy and instructing prosecutors to act on the merits of individual cases.

“Consistent with the longstanding principle of making individualized assessments in criminal cases, I am rescinding — effective immediately, the policy directive,” Wilkinson wrote.

Wilkinson said the department’s principles have “long emphasized that decisions about bringing criminal charges should involve not only a determination that a federal offense has been committed and that the admissible evidence will probably be sufficient to obtain and sustain a conviction, but should also take into account other individualized factors, including personal circumstances and criminal history, the seriousness of the offense, and the probable sentence or other consequences that would result from a conviction.”

The “zero tolerance” policy meant that any adult caught crossing the border illegally would be prosecuted for illegal entry. Because children cannot be jailed with their family members, families were separated and children were taken into custody by Health and Human Services, which manages unaccompanied children at the border.

The memo revokes the Trump administration’s massively unpopular policy responsible for the separation of more than 5,500 children from their parents at the US-Mexico border. Most families have not been prosecuted under zero tolerance since 2018, when the separations were halted, though separations have continued on a smaller scale.

Practically, the ending of the policy will affect mostly single men who have entered the country illegally.

“While policies may change, our mission always remains the same: to seek justice under the law,” Wilkinson wrote in the memo.

President Joe Biden has issued an executive order to undo some of Trump’s restrictive policies, but the previous administration has so altered the immigration landscape that it will take quite a while to roll back all the major changes. Some of the parents separated from their children were deported. Advocates for the families have called on Biden to allow those families to reunite in the United States.