Sean Last completely demolishes it. Fact Checking "Politifact"
Unsurprisingly, in their article Polifact completely ignores the reports issued by Homeland Security's Secure Communities Program which is by far the best source we have on immigrant crime numbers. For the last few years, via the Secure Communities Program, anytime someone is arrested their fingerprints are sent to the DHS which then checks to see if their fingerprints match the fingerprints of any known immigrants in their database. Obviously, this program will under-estimate the number of times that illegal immigrants are arrested because many illegal immigrants will not have their fingerprints registered with the DHS. But a large proportion of them will and this method is clearly better than just asking whether or not someone in jail is an immigrant. Moreover, unlike SCAAP, Secure Communities covers the entire country. The most recent numbers from Secure Communities show that by August immigrants had been arrested 503,000 times in 2014. Given how large this number is, and the fact that we know it is lower than the true number, it seems very safe to say that more than 200,000 non citizens went through our prison/jail system last year. That being said, not all non citizens are illegal aliens. So it is possible, though I think improbable, that less than 200,000 illegal immigrants were arrested in 2014.Let the Hate Facts fall like rain.
Politifact also failed to cover the Homeland Security report that Trump based his claim on. They claimed they couldn't find the report, yet, somehow, journalists at other sites have had no problem locating the document. In it, Homeland Security reports that there are currently 347,000 criminal immigrants in the united states. Now, to be fair, Trump seems to have misunderstood this number. He thought it referred to the number of criminal immigrants in prison. It's actually a much scarier statistic than that because most of these criminal immigrants are in America but are not in prison. They are just roaming the streets. None the less, the Secure Communities data covered above indicates that Trump was correct, even if he mistook this document as saying something more innocuous than what it actually states.