"What is the message on the backs of both their t-shirts?"
I think it reads, "Legal observers - observers legales".
But it was supposed to read, "Proudly Perverting America for the cause of Communism."
The ACLU is out of place there 'monitoring' Minutemen. Why not just separate the Minutemen from ACLU people with team jackets or maybe just 'shirts and skins' or something. It's getting ridiculous. Imagine an illegal stepping across the border to see that scenario. Ha! Crazy Gringos!