I graduated with an LL.M and was on OPT for a year. I have now transferred to H4, but would like to apply for an H1B through a start up law firm in the Bay area. My potential employer tells me that in the past, applications that he submitted for applicants like me (with an LLM, pending bar clearance)were rejected. What are my chances of getting my application approved? Should I try with an established law firm or should I wait and pass the bar?

It sounds like there is a problem in how the case was filed. An H-1B is for a professional position that requires a minimum of a bachelors degree. If they had a denial of an advanced degree (LL.M), then it sounds like the position required more than just a bachelors degree, it needed professional licensing. If the position with the law firm only requires a bachelors degree and you have the degree or the equivalent, you qualify.

The denied case as you describe should never have been filed. Consult with an experienced immigration attorney, it will depend on the position and the minimum educational and licensing requirements. Good luck.

Consult with an experienced immigration attorney who specialized in work visas... this could be complicated. Good luck..