On Capturing Terrorists

The right wing media and Republican congressmen are up in arms at what  happened in Boston. They now claim this is proof that allowing immigrants to enter the United States will result in crime and violence. Republicans insist on tight control of our borders, they want intensive investigation of anyone who comes from an area of the world where there is violence. Listen to Republican demands for background checks on those who might pose potential danger  to society. Of course, the same congressmen oppose any background checks for people who purchase weapons of destruction. They insist to check on possible gun owners violates the Constitution.

I am confused, if society must check on any potential weapon owner who comes   from another land, why don’t we insist on ALL weapon owners being checked out? I assume this means native born Americans who are criminals are protected by the Constitution.