At American Liberty: CATO Pushes Debunked Claim On Illegal Immigrant Crime Rates

American Liberty has put up another of our studies.

The CATO Institute has long pushed for open borders, a stance that contrasts with the views of other libertarians like Milton Friedman, who argued that open immigration only works if the country doesn’t have a large welfare system. In a new report, despite all the evidence to the contrary, CATO again claims that illegal immigrants commit crimes at lower rates than native-born Americans. To support this, they rely heavily on data from the American Community Survey (ACS). But they fail to explain the limitations of this dataset—especially when applying it to crime statistics.

The ACS samples about 3.5 million addresses per year across the U.S., including Washington D.C. and Puerto Rico. Households receive an invitation to complete the survey online, followed by a paper questionnaire if they don’t respond. CATO specifically uses ACS data on prison populations to estimate how many inmates are in the U.S. illegally.

However, using the ACS to estimate the number of illegal immigrants who have committed crimes introduces serious biases. These flaws lead to a systematic undercount of criminal activity among illegal immigrants—distorting the results and understating the true extent of the problem. It is again disappointing that CATO doesn’t address the biases in the data they present.

1. Undocumented immigrants are often deported directly from prison before completing their sentences. For example, in early 2025, approximately half of the individuals highlighted in ICE‘s enforcement actions were already incarcerated at the time of their arrest. The problem that this creates is that illegal aliens will be underrepresented relative to their actual share of the criminals in the prison population. There is also the Rapid Removal of Eligible Parolees Accepted for Transfer (Rapid REPAT) program allowed noncitizens convicted of nonviolent crimes to be released from prison early and voluntarily deported to their home countries.
2. ICE’s Enforcement and Removal Operations (ERO) data indicates that many noncitizens arrested for crimes like DUI, drug possession, or assault were taken into ICE custody directly from local jails before serving full sentences. For instance, in fiscal years 2021–2022, ERO arrests often involved individuals with pending charges who were deported after ICE assumed custody, particularly if they had prior removal orders.
3. Illegal aliens may also be deported after arrest but before they have served time in prison, and that can arise due to policy decisions that prioritize immigration enforcement over criminal prosecution. Given that the illegal alien is already in the country illegally, a conviction isn’t necessary for deportation. This will also ensure that illegal aliens are underrepresented relative to their actual share of the criminals in the prison population. Examples before the Trump administration include, Mario Mata (Texas, 2024) and Jorge Rodriguez-Hernandez (Texas, 2024).
4. ChatGPT summarizes it this way (emphasis added): “Prior to 2025, U.S. immigration authorities frequently deported noncitizens without legal status after arrest but before they served time in U.S. prisons. This approach utilized mechanisms such as expedited removal, ICE detainers, and programs like Rapid REPAT to facilitate swift deportations.”
5. CATO assumed that someone is a legal immigrant if they are receiving any type of federal welfare, health care, or Social Security benefits. But there are problems with this. There is evidence of illegal aliens obtaining these benefits in significant numbers. Regarding Social Security benefits, “In 2013, the SSA Office of the Chief Actuary (OCACT) estimated that about 3.1 million unauthorized aliens were working and paying Social Security taxes in 2010.” Illegal aliens have been prosecuted for fraudulently obtaining Social Security benefits (e.g., here, here, and here). A 2024 audit by the US HHS Office of the Inspector General found California improperly claimed $52.7 million in federal Medicaid reimbursement for capitation payments on behalf of illegal aliens. A Florida state audit found that Medicaid payments to hospitals for the care of illegal aliens totaled $76.6 million. Regarding Florida’s numbers, much of this may have been emergency medical care, and emergency care is covered by Medicaid, but it is unclear whether those who are receiving the benefits understand the distinctions in the law when they answer questions in the ACS survey. In addition, there were 2.7 million asylum seekers in the US in 2024, and HUD has allowed public housing agencies (PHAs) the discretion to provide housing for these individuals. In parts of the country, such as New York, Chicago, and Los Angeles, public housing was occasionally granted to those classified by the Biden administration as asylum seekers. Finally, since this is a survey filled out by respondents, there is the issue of whether illegals understand the difference between a state program such as Cal-Med, which readily covers illegals, and Medicaid, which technically doesn’t cover them. If the illegals are getting state medical benefits for non-emergency care, might some of them confuse that with Medicaid benefits?
6. Whether the illegal aliens identify themselves as illegal aliens is voluntary. Given that deportation is one consequence of them being identified as an illegal, in case the illegal is not already identified as an illegal, it is hard to see why an illegal would voluntarily identify that information. Now illegals will likely underreport their illegal status in this survey whether they are in prison or free in the country and the survey does tell people that the information that they give to the survey won’t be shared with law enforcement, but if an illegal in prison is identified as an illegal while in prison, they will be deported and there will be some illegals who will not trust the claim the data won’t be shared.