The enormous administrative undertaking that would be required to put into effect the deferred deportation program — which some in Congress had hoped to defund — would thus be wholly unnecessary. Indeed, Congress would be impotent to restrict the president’s pardon as the Supreme Court has made clear that “Congress cannot interfere in any way with the president’s power to pardon.” If immigration enforcement agencies or any future administration failed to respect the pardon, individual beneficiaries could use it as a shield in any deportation proceedings that followed.

President Obama has plenty of time left to issue such a pardon. There is solid historical and legal precedent for him to do so. And although it would probably bring about legal challenges, opponents could not use the legal system to simply run out the clock, as they have with his deferred deportation program. A deferred deportation program could be undone by a President Trump. Unconditional pardons, in contrast, are irrevocable.

Finally, some would surely argue that a pardon protecting a large category of immigrants from deportation would, just like the deportation deferral program, effectively amount to a repeal of laws enacted by Congress. However, pardons do nothing to alter the law. They protect certain past offenders from punishment and prosecution, but leave the law unchanged as applied to any future violators.

President Obama has deported around 2.5 million people. That is about the same number as were deported in the entire 20th century. His apparent strategy was to demonstrate his bona fides on enforcement in order to persuade recalcitrant Republicans to work with him on immigration reform. It didn’t work. It turns out that you don’t convince people to be more humane on immigration by deporting immigrants hand over fist.

We are left with a brutal legacy of millions of families torn apart, many simply for doing what they needed to do to protect and feed their children. President Obama will not be judged on his intentions or his attempts on immigration, but rather on his real impact. This is his last chance to establish a legacy of pragmatic compassion.