As Texas Republican Congressman Chip Roy appeared as a guest on CNN's Right Now show, host Brianna Keilar insisted that it is a "fact" that illegal immigrants commit crime at a lower rate than do U.S. citizens as the two debated whether there needs to be a border wall between the U.S. and Mexico.

She also had difficulty understanding the congressman's argument that, even if most drugs are smuggled through ports of entry, having a more secure border would free Border Patrol agents to focus on detecting drugs at the ports.

At 1:50 p.m. Eastern, as Congressman Roy recounted crimes like murder and human trafficking that have been facilitated by border permeability, leading Keilar to jump in:

You know, Congressman, I'd see your point if the CATO Institute -- a libertarian-leaning think tank ... One of the points that CATO made is that immigrants don't -- they commit crimes to a lesser degree than people who are not immigrants -- than Americans.

She then cited reports that illegal drugs are usually smuggled through ports of entry, leading the congressman to point out that, if Border Patrol agents had a lower number of illegal border crossers to apprehend, they could devote more attention to the ports.

After having trouble understanding his point, a bit later, she again brought up the questionable CATO study and asserted that the congressman was refusing to believe a "fact" by having doubts about the study. After Roy again complained about crime and human trafficking, Keilar demanded: "Why raise that specter when the statistics on crime really do not favor the Republican argument here?"

He voiced his disagreement with the study's conclusions, leading Keilar to follow up: "How do you disagree with a fact when it comes to crime -- that it is reduced? And this is according to CATO. This is no enemy of Republicans -- combing through different data and coming to a conclusion, and the conclusion is undocumented immigrants are actually less likely to commit crimes."

The CNN host did acknowledge that libertarian groups like the CATO Institute tend to align more with liberals on immigration issues than with conservatives.