Immigrant advocates argue that the process is both confusing and unnecessarily duplicative. “It’s wasteful from a taxpayer dollars perspective and makes an already harsh enforcement system doubly harsh,” said Heidi Altman, the policy director of the National Immigrant Justice Center.

But proponents of the law say that it is important that there be real consequences to convey the seriousness of the offense.

But most illegal crossers are not prosecuted

Even under the Trump administration’s “zero tolerance” policy, under which prosecutions shot up by about 40 percent, only a fraction of those who crossed the border illegally were prosecuted for doing so. The cases place a heavy administrative burden on federal judges, prosecutors and public defenders.

Operation Streamline allows for mass hearings in which dozens of migrants are processed at once — usually entering guilty pleas — often after only a brief discussion with a public defender. The hearings have been criticized by immigrant advocates who argue that they deprive migrants of their legal rights to due process.

Still, Streamline prosecutions have overwhelmed many of the nation’s federal courts. In the Southern District of California, for example, the court converted part of a garage to make space for more illegal entry prosecutions, and created a separate courtroom that is staffed in part by government lawyers who are on loan from Customs and Border Protection, rather than local federal prosecutors, to handle the increased workload.

Repeat offenders face more serious consequences

The Democratic candidates differ over whether they would go further down the decriminalization road to eliminate a second provision of the United States federal code, 1326, which makes illegal re-entry into the United States a much more serious felony offense, punishable by up to 20 years in prison and a fine. Some argue that provision is necessary to discourage people who have been deported from returning to the United States over and over again.

Regardless of whether they are prosecuted, though, people who are deported face civil penalties if they return and are caught. Already under the current law, anyone who is placed in “reinstatement proceedings” — meaning that they have been deported in the past — is ineligible for asylum and the pathway that comes with it to legal permanent residency and, eventually, citizenship.