The zero tolerance policy applied to all adults, whether they crossed the border alone or with their children. If they had children with them, the children were sent to detention centers and the adults went to jail.
Here is what the new executive order does and does not do:
Allows families to be detained together under DHS authority
According to the order, families who are detained for illegally entering the country together will be put into the custody of the Department of Homeland Security. This is different from the previous practice, which sent adults who entered the country illegally to the custody of the Justice Department where they were criminally prosecuted. If they entered with children, the children were put in the custody of the Department of Health and Human Services.
The DHS is now charged with keeping families together in custody until the criminal case against the adults and the immigration case against the family are completed.
The executive order says families will stay together "where appropriate and consistent with law and available resources."
Moves immigration cases of detained families to the front of the line
The new order directs the Justice Department to prioritize (or move up in line) the cases of migrant families. This means other immigration cases can be pushed back. A backlog already exists in immigration courts. Those courts are run by the Justice Department.
Orders Jeff Sessions to ask a federal court to allow families to be detained for as long as necessary
The order calls for U.S. Attorney General Jeff Sessions to ask a court to reverse a decision that required the federal government to place children brought into the country illegally with a close relative or family friend "without unnecessary delay," and to keep children in the "least restrictive conditions" possible if they do not have a family member of friend to take them.
Sessions' request for the reversal of the court decision on the Flores settlement can lead to a situation where the government would be able to detain families for as long as it took to get the criminal and asylum cases to work their way through the system, despite the fact that those cases will be given priority.
The Flores settlement, which began as a class-action lawsuit, addressed migrant children being kept with their parents and those in the country without their parents and set the time they could be held in detention at 20 days.
Orders other federal agencies to set up detention centers
The Department of Defense and other federal agencies have been put on notice that facilities that house families will need to be prepared. According to the Washington Post, Lt. Col. Jamie Davis, a Pentagon spokesman, said three Defense Department locations in Texas Fort Bliss, Goodfellow Air Force Base and Dyess Air Force Base, and one in Arkansas, Little Rock Air Force Base, are being considered for use in housing migrant families.
What it does not do:
Doesn't reunite already separated families
The order did not spell out what would happen to some 2,300 children already separated from their parents since the zero tolerance policy went into effect in April.
"It is still very early and we are awaiting further guidance on the matter," Brian Marriott, HHS' families division's senior director of communications, said Wednesday. "Our focus is on continuing to provide quality services and care to the minors in HHS/ORR funded facilities and reunifying minors with a relative or appropriate sponsor as we have done since HHS inherited the program. Reunification is always the ultimate goal of those entrusted with the care of UACs, and the administration is working towards that for those UACs currently in HHS custody."
>>Trump ends migrant family separations: Read the executive order
In this June 20, 2018, photo, President Donald Trump gives the pen he used to sign the executive order to end family separations at the border to Homeland Security Secretary Kirstjen Nielsen, left, as Vice President Mike Pence, right, watches in the Oval Office of the White House in Washington. Nielsen has one hard-earned presidential signing pen, receiving hers after Trump used it to sign the executive order. By the time Trump reversed his policy Wednesday, Nielsen had been both yelled at and praised by Trump and pilloried for repeating his falsehoods. (AP Photo/Pablo Martinez Monsivais)