What niche could you possibly have other than teaching Pharmacy Law (Fred Weissman, PharmD/JD - USC) or work as an attorney or as a pharmacist.
One PharmD/JD I know practices law...and has nothing to do with pharmacy other than occassional clients who are pharmacists but he could be doing what he's doing without the PharmD. He certainly can't make a living working strictly with pharmacists only.
Many other PharmD/JD I know practice pharmacy because they make a better living as pharmacist.
Malpractice law or healthcare law? You don't need a PharmD to do it.
If becoming an attorney is your aspiration, then go to law school. I can't think of too many areas of practice of law that can be benefitted by having a PharmD....especially since if an attorney requires an expert witness, an expert PharmD in a certain field can be retained to provide expertise. If I was an opposing attorney arguing against a general PharmD practitioner/JD, it wouldn't be very difficult to tear apart your credentials..
"So Mr. PharmD/JD...it says you've worked as an intern at a retail pharmacy for 3 years and have graduated with a doctor of pharmacy degree from ***** pharmacy school. But you have never worked in a critical care setting ...