In the last few years, numerous states have already begun to, or soon will, issue driver's licenses to illegal aliens.  Spurred by concerns about national security risks, Trump's Department of Homeland Security is finally investigating whether these licenses are pathways to dangerous identity fraud.

The plethora of licenses in the hands of illegal aliens has worried those concerned about voting integrity.  In California, for example, the current iteration of the "motor voter" law means that anyone who obtains or renews a driver's license is automatically registered to vote.

Technically, "[i]ndividuals with AB 60 driver's licenses are not eligible to participate in the California Motor Voter program and are not eligible to vote."  In practice, last year, the DMV admitted that it erroneously registered 1,500 drivers to vote, including, it said, non-citizens (i.e., green card–holders and illegal aliens).  (If you're wondering whether 1,500 is a real number, you'll find interesting Jeff Carlson's article about California's overwhelming support for Hillary in 2016.)

California's not alone.  A July 2019 article from the National Conference of State Legislatures has noted the trend:

Thirteen states and the District of Columbia enacted laws to allow unauthorized immigrants to obtain a driver's licenses. These states—California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maryland, New Mexico, New York, Nevada, Utah, Vermont and Washington — issue a license if an applicant provides certain documentation, such as a foreign birth certificate, a foreign passport, or a consular card and evidence of current residency in the state.

[snip]

In 2019, legislators in several states introduced legislation to provide driver's licenses to undocumented residents [sic] including Florida, Kansas, Massachusetts, Minnesota, New Jersey, New York, North Carolina, and Texas. The Oregon House passed legislation in June 2019 which would provide licenses to undocumented residents.

The proponents of this push to give legal driver's licenses to illegal residents insist that the public will benefit:

Proponents of extending driver's licenses to immigrants argue that licensing undocumented residents [sic] will lead to fewer hit-and-runs, more trust between immigrants and police, and increased revenue for Departments of Motor Vehicles.

To date, there do not seem to be any studies confirming these optimistic predictions.

The good news for those who worry that handing out official government documents to illegal aliens creates opportunities not just for voter fraud, but for national security risks is that Trump's Department of Homeland Security is also getting worried.  On Tuesday, acting Homeland Security secretary Chad Wolf initiated a study looking at whether these licenses negatively affect the federal government's law abilities:

Wolf's memo, which went to agencies including U.S. Customs and Border Protection and the Transportation Security Administration, follows a New York law authorizing licenses for undocumented immigrants [sic] and restricting data-sharing with federal agencies. Similar laws exist in a dozen other states, including New Jersey, which passed a similar measure in December.

Wolf wrote in his memo that the department needed to be "prepared to deal with and counter these impacts as we protect the homeland." He also asks each recipient to take account of what Department of Motor Vehicles information is already available, and of any security consequences their operations could risk without that data, according to the AP.

So far, those who blithely predicted all sorts of societal benefits from legitimizing illegal behavior have been unopposed.  It will be interesting to see what actual data reveals once the DHS has had a chance to look at the data and determine whether licenses for illegal aliens are being used for good or ill.