During the debate, Obama said:

What I’ve also said is if we’re going to go after folks who are here illegally, we should do it smartly and go after folks who are criminals, gang bangers, people who are hurting the community, not after students, not after folks who are here just because they’re trying to figure out how to feed their families. And that’s what we’ve done. 

Julianne Hing corrects the record:

[D]ata collected over Obama’s tenure show that among the close to 400,000 people who are deported annually, far from being “gangbangers,” the vast majority have no criminal record whatsoever.

In preliminary data for the January-March 2012 quarter collected by the Transactional Records Access Clearinghouse, for example, just 14 percent of those deported had any criminal record. (Immigration violations are typically considered civil violations, and do not constitute a criminal offense.) But, a closer look at the data shows that just 4 percent of those deported had a so-called “aggravated felon” on their record, an immigration court-specific designation of crimes that can include crimes as serious as rape and murder, but has also been expanded to include violations like theft or non-violent drug offenses.

Adam Serwer adds:

It’s true that sometimes minor offenses can be used to target people who are actually suspected of more serious crimes. The reality, though, is that there just aren’t more than a million undocumented “gang bangers” in the United States, and had Romney used similar phrasing to describe undocumented immigrants, the left probably wouldn’t forgive him for it. 

Update from a reader:

I work as a public defender in a small rural town, with a fairly large Hispanic population. I always ask my Hispanic clients whether they are documented and legally permitted to live in the United States. Because if they are undocumented, then the minute they step foot in jail, the INS will place a hold on them and deport them. From my personal experience, this administration is aggressively deporting any undocumented residents who find themselves in jail. As such, I always try to arrange plea agreements that allow my undocumented clients to avoid jail time, perhaps by paying a larger fine or doing more community service work.