Here is a great article on the topic from
Rolling Stone.
https://www.aclu.org/know-your-right...order-zone-map
"Asked to clarify CBP's authority over domestic passengers, the spokesman replied that "at this time this is all I have."
Rolling Stone asked CBP to clarify whether the CBP document search was truly a "request" – or instead a legally binding demand by the agents. The spokesman again could not clarify CBP's legal authority, warning only, "It is always best to cooperate with law enforcement, so as to expedite your exiting the airport in a timely manner.""
Also of interest: "Rolling Stone asked the New York Civil Liberties Union for its understanding of the law in this incident. NYCLU Staff Attorney Jordan Wells writes that "CBP does not have carte blanche to refuse to let people off a domestic flight until they show ID." His advice: "While one may choose to produce identity documents to avoid further hassle, it is important to remember that in the United States people have a constitutionally protected right to remain silent.""