Yeah, this article appears to misrepresent what we've been told about the Caldari legal system before, and doesn't really fit into the framework, at least as I've envisioned. I think there could be civil rights groups, but the whole process described here...the Provists might arrest someone without cause, but then it would be their corporate lawyer going to bat for them because of violations of corporate sovereignty as other people have pointed out, not because of an American-style Fourth Amendment violation.
I do think that the Caldari have some sort of basic civil rights that all corporations are expected to abide by -- slavery is illegal, after all, and I suspect enshrining the sanctity of private property (even if private property is hard to acquire) is very high up on the list of Caldari rights. And, based on the CBT corporate description, I'm not sure they have attorney-client privilege or anything like that either -- does France have rules of that nature (since I know they have an inquisitorial judicial system as well)?
But yeah....this article isn't the best I've seen when it comes to portraying the Caldari legal system -- somewhat understandable, though, since I don't think there's any easy analogue compared to the other empires (same problem as the Caldari government in general).