REAL-ID is effectively a national ID card. Organizations like EFF and ACLU have been opposed to REAL-ID on privacy and civil liberties grounds since it was passed in 2005. Libertarian groups like Cato also highlight that it's a huge unfunded mandate on the states. Overall, resistance to REAL-ID has been one of the most effective multipartisan civil liberties efforts - a lot to learn from it.

Here's EFF's page: https://www.eff.org/issues/real-id

And Cato's most recent commentary, by Jim Harper: http://www.cato.org/publications/commentary/real-id-decision...