There has been a lot of misinformation spread around the internet about what Texas can and can't do. Being a history buff and having studied Texas history maybe I can shed some light on the subject for your readers.
Texas was an independent country for 9 years before joining the United States, unlike California which was not recognized by other countries and immediately joined the United States. Texas was recognized by England, France and other European countries and had foreign embassies. In fact you can go to London today and see a placard that marks the site of the Republic of Texas Embassy.
Texas entered the U.S. under a treaty signed by both countries. Under this treaty Texas retained certain rights not held by other states.