This is Greenwald's take on the border search phenomenon.

In essence, the bargain offered by the state is as follows: if you meaningfully challenge what we're doing, then we will subject you to harsh recriminations. But if you passively comply with what we want, refrain from challenging us, and acquiesce to our prevailing order, then you are "free" and will be left alone. The genius is that those who accept this bargain are easily convinced that repression does not exist in the US, that it only takes place in those Other Bad countries, because, as a reward for their compliant posture, they are not subjected to it.

What makes this tactic particularly effective is that it will not affect those who have no interest in engaging in real dissent against the government. If you're not a filmmaker who challenges the prevailing government narrative (Poitras), or a scholar trying to understand rather than demonize currents in the Muslim world (Abidor), or a lawyer involved in groups suing the US government for unconstitutional behavior (Wayne), or an activist advocating for WikiLeaks and working to protect online anonymity and thus thwart government spying and control of the internet (Jacob Appelbaum), or someone who supports Bradley Manning's legal defense (David House), then you're not going to be subjected to this sort of intimidation and rights-invasions, and it's thus easy for you to simply assume that it does not exist.

Although this sounds shrill, where the rubber meets the road with this concern regards the use of TSA, rather than CBP. Jacob Appelbaum has reported publicly that he is subjected to additional scrutiny by TSA whenever he boards an airplane. I've heard similar reports from others.

The constitutional context for the authorization of TSA searches is protection of the security of flights. The TSA only has a legal authority to search people's effects without probable cause insofar as the purpose of those searches is to protect the security of flights and is narrowly tailored to that purpose. It is unconstitutional for the TSA to perform searches for other law enforcement purposes without meeting the Fourth Amendment's warrant and probable cause requirements. The TSA cannot, for example, perform searches for the purpose of locating illegal drugs. That is absolutely unconstitutional, no matter what you might have heard to the contrary.

It is not clear that the list of dissidents and activists Greenwald mentions present a risk to the security of flights. No matter what you think of Jacob Appelbaum, the idea that he represents a risk to the security of flights is dubious. Therefore, if the TSA is monitoring Jacob Appelbaum and subjecting him to additional scrutiny every time he flies, that scrutiny may violate his Constitutional rights. Whatever the rationale for the scrutiny, if it isn't related to the security of flights, it is not legitimate.