Explanation of the law in the TX Confederate flag license plate case.

Here's the legal background in a nutshell.
"Because Texas allows more than 300 civic organizations to buy space on its license plates, free-speech advocates say that the state has created a limited public forum in branded logo plates. If that’s right, the sons of Confederate veterans who want to put the Confederate battle flag on a license plate should win their case. The government can’t favor nonracist speech over racist speech, because racism is a viewpoint, albeit a nasty one.
But that’s only half the legal story. On the other side is a separate doctrine, known as the doctrine of government speech. According to this principle, if the government is speaking, and not a private person, then the free-speech clause doesn’t apply at all. The government is under no obligation to speak neutrally. It can advance any viewpoint it wishes, provided that viewpoint isn’t itself unconstitutional.
Courts love the government speech doctrine because it enables them to make difficult free-speech cases disappear. In the Texas license plate case, it means the state could express any view it wants on its license plates without worrying about embracing any one viewpoint. If the logos on the plate are government speech, Texas wins.
At this point you may be getting frustrated with me, or rather with the Supreme Court. “Come on,” you say, “this isn’t simply a limited public forum or simply government speech — it’s obviously both!”
Well, yes. But the Supreme Court’s judicial doctrine hasn’t really clarified what would happen if the case presented a true hybrid between a limited public forum and government speech. The law insists on slotting every example into one of the two boxes. And which doctrinal box the court chooses dictates the outcome of the case."

This is a toughie.  In a close case I believe that constitutional rights should always prevail.  I believe Texas has created a limited public forum.  This being so, it cannot discriminate against viewpoints.  It must allow the rebel flag plates.  The solution is to abolish the specialized plates option.