One of the first actions Trump took when he entered office was to issue an Executive Order (EO) instituting a travel ban that generated confusion and caused havoc at border entry points across the country. Dozens of lawsuits were filed against the ban, and its implementation was quickly halted in federal court.
In response, Trump issued another EO in March, which, while not as destructive or as blatantly discriminatory as the first, still generated concerns about its Constitutionality.