Does a medical emergency justify using HOV lane in San Diego, CA.?

I corrected the Practice Area to Criminal Defense. I believe that the Defense of Necessity clearly applies here to allow you to break a minor criminal law to prevent much greater harm. I'd also ask yourself why you didn't need an ambulance; it seems that both you and the officer are in denial.

Maybe. Necessity defense could apply, but the cop is going to say there was no medical emergency. It's a ~$500 ticket that doesn't carry a negligent operator point.

There is a defense of necessity... But to use it, you cannot have caused the emergency yourself and your actions must have been essentially the only choice. By declining emergency treatment, you have all but said that it really wasn't an emergency. There are two different carpool violations - one for crossing the lines (that one is a moving violation and a point) and traveling in the lane without enough people (not a point). If you're charged with the moving violation and you want to try your necessity defense, I'd suggest a traffic ticket attorney and getting all your medical records and proof that you spoke with a nurse that advised you to come right in.

This is an issue the trier of fact will need to decide. That is the judge. You will need to go to trial on this and provide proof the the emergency. You will not be able to testify as to what the nurse hotline said to you as that is hearsay. Best of luck.

Possibly a defense of necessity here. Documentation of the emergency and a good defense attorney will help.