A DMV refused to issue a man a driver's license because his signature was upside down.

What do they care? The important thing about a signature is not that it be legible (mine certainly isn't) but that it be difficult to forge. Sounds like a good technique to me.

So, burqas are okay, but upside signatures are not?

My dad God rest him, was the president of the Boston Stock exchange. He taught me at a very early age that whether your signature was legible or not was immaterial what is important is that you can reproduce it and that others cannot. I have passed on this wisdom to my daughter who I hope will pass it on to her children. What we have here is a group of bureaucrats who collectively have less common sense than my daughter has at her tender age. She ingeniously and up until now I thought uniquely taught herself to sign her name upside-down. I'll let you know in a year how thing go at my own DMV...

How about if someone wants to start signing their name in Hebrew, Arabic, Japanese or some other non-latin script?

How did the Prince Rodgers sign stuff when he was going through is typographical dingbat phase? For that matter, what do various celebrity mononyms do?

How about who claims to be illiterate, and makes an "X" witnessed by two people?

This guy reminds me of a college roommate I had briefly-- he decided that wearing different florescent, non-matching socks was a deep philosophic statement. Of what, I was afraid to ask. But in both cases, their motivation seems to be an insecure, juvenile pleasure in getting away with something trivial.

Raoul, all of the above are acceptable. Again, the purpose of the signature is to be unique and difficult to forge, not to be legible.