The Florida Georgia Line is not just a country music act, it’s an illustration of the constitutional right to travel. People traveling between states don’t have to stop and show a passport every time they get to a state line.
The right to interstate travel traces back to the Articles of Confederation: “the people of each state shall have free ingress and regress to and from any other state....” [Article IV]. You won’t find the right to travel in the text of the U.S. Constitution, but it’s now considered a fundamental right, one of the privileges and immunities of U.S. citizenship under the 14th Amendment. Courts have deemed the right to interstate travel a fundamental right since at least 1823, but it wasn’t until 1999 that the Supreme Court finally located the right in the privileges or immunities clause. [Saenz v. Roe]
Because the right to interstate travel is a fundamental right, it is given the highest level of constitutional protection. Laws that impinge on the right must pass strict scrutiny, that is, they must serve a compelling government interest, be narrowly drawn, and use the least restrictive means to achieve their purpose. All sorts of laws have been knocked down as offensive to the right to interstate travel - harbor taxes, a ban on bringing indigent persons into a state, restrictions on the use of highways and public accommodations on the basis of race, and limitations on state welfare benefits and voting rights for new residents. But the right to interstate travel, like every other right, is not absolute, and the Supreme Court has upheld simple state residency requirements that don’t have time periods attached, even if they might arguably discourage interstate travel - some voting restrictions, divorces, public employment, and free public education being some examples where simple residency requirements have been upheld. [Chemerinsky, Constitutional Law - Principles and Policies, 4th Ed., pp. 878-889]
What about the right to travel in our current circumstances of concern over coronavirus? President Trump said this past week he is considering travel restrictions to California and Washington, two states among the hardest hit so far. The analysis is similar to assessing whether a quarantine order is constitutional, as I reviewed with you three weeks ago. Courts will generally uphold quarantines and travel restrictions for public health reasons as long as those reasons are not arbitrary or oppressive. [People ex. rel. Barmore v. Robertson, 134 N.E. 815, 817 (citations omitted) (Ill.1922)] In 1965, the Supreme Court said the right to travel “does not mean that areas ravaged by flood, fire or pestilence cannot be quarantined when it can be demonstrated that unlimited travel to the area would directly and materially interfere with the safety and welfare of the area.” [Zemel v. Rusk, 381 U.S. 1, 15 (1965)] The CDC maintains Do Not Board and Lookout lists for sick passengers and those lists probably pass constitutional muster when viewed through the public health lens.
The right to foreign travel is on a different constitutional footing and is given less protection. Foreign travel is not a fundamental right. Therefore, restrictions on foreign travel do not have to meet strict scrutiny; they only have to pass the rational basis test. Very few governmental actions ever fail the rational basis test. So Trump’s travel ban on foreign nationals from European illness hot spots and the medical screening of Americans returning from those locations would more than likely be upheld in court as showing some semblance of rationality, screams from civil libertarians notwithstanding.