H4 pending to H1B

I got a job offer four month ago. I was told that I can not apply for my H1-B,
because my status is H4 Pending. I filed my I539(from F1-opt to H4) on June last
year when my OPT almost expired. It already 8 month, my case is still pending. My question is " Can I apply for H1B with my H4 pending status?" If yes, where
I can find the law evidence. So I can convince my lawyer

Thank you so much.