One thing I've always wondered is how scope of practice between board-certified physicians is enforced? Like say I'm a trained general surgeon, but I perform brain surgery. What happens, do I just get sued for malpractice (assuming something goes wrong because I don't have the training to do what I'm doing)? Or can will my board or the board for the scope of the procedure I did come after me? And how is this decided in more borderline cases, like where dermatology and plastic surgery might intersect or vascular surgery and IR?
Scope of practice can be hammered and narrowed at every possible level. Eg. Individual, hospital/clinic, medical board, licensing board, insurance carrier, payers.
To use your example: if you're a general surgeon and you do brain surgery (and it goes wrong),
-You individually will be sued
-Your malpractice insurance carrier will likely not cover you, as your insurance premium is based on a general surgeon's typical scope of practice. they might also just drop you for doing something so stupid.
-The payer (e.g. what insurance company the patient has) will not reimburse for a procedure not done by a qualified neurosurgeon.
-the hospital system may not allow you to schedule the procedure up front or just strip your regular surgery privileges afterwards.
-the licensing and medical boards may cite you and/or suspend your licenses and certifications for not practicing safely outside the scope of practice.
Basically it's not worth it to stray too far outside your scope of practice because you'll be up **** creek without a paddle.
However, there are plenty of borderline situations in medicine where there is substantial overlap in services. A dialysis catheter can be placed by anyone who can put in a central line. Dialysis AVF work can be done by vascular surgery, IR or interventional nephrology. For the most part, it's pretty clear to those in said fields what constitutes exceeding their scope of practice. IR ain't gonna do an open-AAA repair. Vascular surgery isn't going to embolize the liver.
Furthermore procedure encroachment is a real thing. VIR basically invented and popularized catheter based work. Cardiology immediately took the cardiac work. Vascular surgery took peripheral arterial disease (and lately it seems cardiology is also trying to horn in on cold legs too).