Throughout Barack Obama s presidency, he justified the record number of deportations carried out by Immigration and Customs Enforcement by pointing to the high number of criminals deported.

Were going to keep focusing enforcement resources on actual threats to our security, Obama said in a 2014 speech announcing executive action to shield parents of U.S. citizens from deportation. Felons, not families. Criminals, not children. Gang members, not a mom whos working hard to provide for her kids.

By Obamas last year in office, publicly released data showed that 58% of deportees had a criminal conviction. More than 99% of deportees met one of the agencys removal priorities.

But data obtained this month by HuffPost through a Freedom of Information Act request reveals the most serious crime committed by more than half of the migrants arrested at the border and tagged as criminal deportees during Obamas second term was entering the country without authorization.

In other words, the difference between those slapped with a criminal immigration offense and those with a clean record was that the Justice Department chose to prosecute them simply for crossing the border. Immigration violations were the most serious crimes committed by tens of thousands of others deported from within the United States and classified as priority removals over that period, despite the fact that their records differed little from non-criminals. Some 2020 Democratic candidates, including Julin Castro and Elizabeth Warren, are pledging to repeal the laws that make this possible.

The data underscores the degree to which skyrocketing prosecutions for border-crossing violations over the last decade helped criminalize a vast swath of the deportee population, giving the impression that they posed a greater public security threat than their records indicate.

Theyve been turning mere immigration law violators into criminal aliens for years in order to inflate the amount of individuals that have been removed under criminal grounds, immigration attorney Matthew Kolken told HuffPost. These were freshly minted criminals. They werent committing crimes in the United States.

While convicts made up nearly half of those deported from the border region from 2013 to 2016, the data makes it clear that there werent hordes of violent criminals. Traffic violations accounted for the second-highest number of criminal convictions for border deportees, making up 11% to 14% for those years.

The data provided by ICE included only broad categories of crime, but previous reporting indicates that driving while intoxicated and driving without a license make up the vast majority of traffic violations on deportees records. Only 15% of border deportees under Obamas second term had a conviction more serious than an immigration or traffic offense.

A much smaller percentage committed more serious crimes. Far less than 1% of criminal migrants from the border and interior combined were convicted of a crime involving homicide, for example. Agency statistics include some deaths resulting from negligence or car crashes under that heading.

Im seeing padding of the number of the people they consider to be criminals with a lot of low-level traffic violations and immigration violations, said Douglas Massey, a Princeton sociology professor and co-founder of the Mexico Migration Project, after reviewing the data. The criminal categories are vastly inflated. The violent crimes are really small in number.

Under Obama, ICE produced end-of-year reports that highlighted the number of criminals the agency deported, trumpeting the high percentage of convicted criminals. Those reports divided deportees removed from the interior from those expelled from the border region largely because the agency considered those arrested while trying to cross into the country a deportation priority regardless of whether they had criminal records.

But the agency did not release detailed statistics over the Obama presidency detailing what convictions had marred individual migrants records. Instead, ICE used a system of priority categories for those deported from the interior and recorded only whether border deportees had a criminal conviction or not.

The sharp rise in prosecutions for border violations that began under George W. Bushs presidency explains the statistical sleight of hand.

In the United States, deportation is handled under civil laws by immigration authorities such as the Border Patrol and ICE. But crossing the border without authorization is also a federal crime, punishable by up to six months in prison. Re-offenders can face felony charges.

The law criminalizing illegal entry, authored in 1929 by segregationist Sen. Coleman Blease of South Carolina and now known as Section 1325, made up a tiny fraction of federal prosecutions by the 1990s. Instead, Border Patrol agents routinely walked unauthorized migrants back to the other side of the border or referred them for deportation proceedings in immigration court.

But starting in 2005, the departments of Justice and Homeland Security teamed up to create Operation Streamline, a program to prosecute migrants en masse for jumping the border , in an effort to route Central American migrants into federal jails and create a new deterrent. By 2008, immigration prosecutions had swallowed up half the federal criminal docket a statistical trend that held true through Obamas presidency.

President Donald Trump ramped up the system further by enacting a zero tolerance policy, mandating all five federal districts that touch the border to focus still more resources on immigration prosecutions. Last year, Trump used the laws criminalizing illegal entry and reentry to carry out his widely reviled experiment with systematic family separations at the border last year. By prosecuting migrant parents traveling with their children, Trump officials channeled them into federal jails, leaving their children in the custody of immigration agencies.

Immigrant rights groups and criminal justice reformers have long argued that the laws needlessly criminalize migrants, drive the expansion of privatized prisons and slap a redundant punishment on people who will have to face deportation proceedings regardless of whether they get prosecuted for illegal entry.

But advocates have also long suspected that the skyrocketing illegal entry prosecutions helped both the Obama and Trump administrations pad their stats to make the deportee population appear like more of a threat than it actually is.