During training, they told me it was illegal in California, but I just recently found out that another buddy of mine that I used to work with is certified. We're trying to figure out a time and place to go on a beach dive.
I did a little research and found that Laguna Beach is the only place (that I could find) that has a "No Solo-Diving" law ($500.00 fine for noncompliance).
I realize that solo-diving is frowned upon by most dive instuctors, but there is no real data to prove whether it is safer/less-safe than diving with a buddy.
My wife is my dive buddy, but there are times when she doesn't feel like diving. Going solo actually is a lot less streesful for me because I'm not constantly worrying about her. If I ever had a problem, I honestly wouldn't want her risking her life to try and save me. She knows if somehow I don't make it back up that I went out exactly how I wanted to!