Father John Whiteford has a great post on Texan independence from Mexico, which has, among other things, a picture of my favorite Texas Founding Father, Lorenzo de Zavala. Zavala, perhaps Mexico's most brilliant politician and diplomat in the period leading up to the war, threw his lot in with Texas because Santa Anna refused to accept the Mexican Constitution. He signed the Texas Declaration of Independence and was the first Vice-President of Texas's interim government. The chief reason for the revolt against Santa Anna -- which is what the Texas War of Independence was -- can be found in the fact that Santa Anna was a despot who arbitrarily violated constitutional law. This is why there were Mexican patriots -- true sons of Mexico like Zavala -- on the side of Texas in the war. I would hope that the same situation would arise if Congress were to give the President power to dismiss Congress and the Supreme Court, a power that was then exercised to establish universal martial law (which is effectively what happened in the case of Santa Anna). And as Whiteford notes, Texas was not the only part of Mexico to revolt against Santa Anna over this point: it was just the only one that managed to succeed, due to the capture of Santa Anna at San Jacinto and to the fact that Texas eventually joined the U.S.
Note especially the flag flown at the Alamo, which Whiteford shows in his post. It bears on it the number '1824' -- the year the Constitution of the United Mexican States was adopted. You can read that Constitution online in both Spanish and English.
[UPDATE: Since this was nominated for the History Carnival, I should point out its companion post on Juan Seguín. Zavala and Seguín are an interesting juxtaposition; looking at the matter through Zavala's life shows the Texas revolution in a very good light, whereas Seguín's shows how messy and complicated and sometimes nasty it could be.]