Federal law makes it a felony to provide remuneration to someone to order or recommend a product or service paid for with federal health care dollars. It also makes it a felony to receive money for the purpose of recommending or ordering a product that is paid for with federal health care dollars. The law is known as the antikickback statute and it places drug companies, device manufacturers, doctors and even nurses within the orbit of liability.
Payments that do not appear on their face to be bribes may indeed be problematic. Consulting agreements, promotional speakers events, and even grants can violate the law. Promotional speakers events are highly likely to violate the law.