Today, it's illegal immigration and border control. A ways back, it was Terri Schiavo. Before that, Elian Gonzales.
Other people have humorously added other examples, but these generally have not had the same wide-spread "infection" of unrelated threads.
I am not arguing one side or the other on the issue. however, as a public service, I will point out that dragging every thread, regardless of subject matter, into the debate is a sure way to alienate (no pun intended) people who might have actually agreed with you, but don't want to be associated with someone who is making a nuisance of themself.
But with this particular issue as with the so-called "war on terror" tain't funny.
Beyond sovereignty and our heritage there's the very foundation of our political process: can we trust our leaders?
The mainline Republican absolute refusal to be honest about why they absolutely refuse to enforce their own laws is maddening.
(Yes! I know the Rats are worse! Thank you, Nelson. I can hear you all the way up here.)