Doctors in New Jersey do not have to tell patients whether they have malpractice insurance for a surgery they are recommending, the state Supreme Court ruled on Tuesday. The high court was ruling on a lawsuit filed against Richard A. Kaul, an anesthesiologist who for years performed back surgeries in same-day operating centers in New Jersey even though he lacked training to operate on spines. Kaul, who once had a practice in Pompton Lakes, lost his medical license years ago after an investigation by state authorities, who had received a series of complaints from patients in severe pain after surgery.