It notes that a border search is one to which courts have said that the 4th Amendment does not apply at all. The border searcher needs not even a hope of finding some no-no before searching, much less slight suspicion, reasonable suspicion, probable cause or anything else.
Technology may cause the courts to take a new look. If the ACLU has its way, a good reason may be the test. That ought to give us a good objective standard.
A bit more seriously, I would submit that any standard at all, other than none at all, would give the courts some flexibility in oversight of the authorities.
http://www.nytimes.com/2012/12/04/busin" onclick="window.open(this.href);return false; ... 21203&_r=0
Jim