People who illegally crossed the Mexico-U.S. border turn themselves in to U.S. Border Patrol agents near McAllen, Texas, May 9, 2018. REUTERS/Loren Elliott

A leaked photo showed 37 people accused of illegally entering the United States, shackled at the hands and feet, being processed at once.

The photo, which was leaked to the media, was taken at the Lucius D. Bunton Federal Courthouse in Pecos, Texas, and showed an unusual glimpse of "Operation Streamline,” a system in which 70 illegal immigration cases can be charged and sentenced at once, reported Business Insider.

Though taking and broadcasting photos in courtrooms is illegal in the U.S., the picture was first sent to Debbie Nathan, a journalist in Texas covering the U.S.-Mexico border and then published in the Intercept.

Nathan said the leaked image has been in circulation among attorneys and legal workers around Texas since April.

She added such mass trials were seen even in magistrate courts in the Texas cities of Brownsville, Laredo, and El Paso. While illegal immigrants in Brownsville were in street clothing, those in Laredo and El Paso were in orange jumpsuits, the journalist said.

Nathan described in the Intercept a judge sentenced as many 40 defendants in one go in Brownsville.

Defendants were asked questions like: "Are each of you satisfied with the help of the lawyer? Has anyone offered you anything or threatened you?" and they had to answer in unison.

She said mass trials were happening since Operation Streamline came into force in 2005.

Operation streamline makes it compulsory for all undocumented immigrants crossing the southern border to be prosecuted through the federal criminal justice system.

Donald Trump’s "zero-tolerance" immigration policy — in which even those crossing the border fleeing violence would be prosecuted — is making such scenes more common.

Magistrates’ courts in Brownsville turned into a “zero tolerance” factories in late April and criminalized migrants, many of whom have no prior criminal record.

Ronald G. Morgan, Federal Magistrate Judge, told the Intercept he often dealt with 35 defendants at once. The government was also breaking up families of immigrants by sending the children to detention centers or distant foster homes.

Federal magistrate Ignacio Torteya III, and Morgan usually saw three and eight of these people a day in turns before the “zero tolerance” policy began, and most pleaded guilty.

On May 7, Attorney General Jeff Sessions announced government will prosecute 100 percent of illegal southwest border crossings and said defendants fleeing violence to protect their young children or seeking asylum would also be tried. He added children would also be separated from their parents.