All of these "post- 9/11" laws and programs, here and abroad, were and are justified as having the goal of protecting against violent attacks on the citizenry.
None were introduced, discussed, or assented to with the understanding that they could be bent and stretched and used to catch naughty journalists or track down leaked documents, or even to hunt for drugs or credit card fraud.
Curiously, the whole boatload of these sweeping powers, in the U.S., anyway, was all ready to go as soon as the bombs went off.
And this is exactly why people objected on grounds of civil liberties, and why the U.S. has the guarantees in the Bill of Rights.
It is not conjecture or possibility, but a FACT that powers allotted to authorities are not merely used for what they are claimed or intended to be for, but for whatever they MAY be used for, because people act in bad faith.
They pretend one motivation, while acting on another. It's not just "the bad people" who do it. It's part of human nature, and one we are rightly wary of.
Therefore, if government can stop, detain, and confiscate the property of a person based on unsubstantiated suspicion, they can do that for no reason, for any reason, and for the "wrong" reasons, and will do so.
Here we have a perfect example. An anti-terror law used with no regard whatsoever for any notion of anything anyone speaking honestly regards as terrorism. And already we see the excuses and deflections, both from authorities and from those who foolishly think they can benefit from the abuse of authority, when the result is convenenient to them.