You've got a patient going through extreme DTs (1). Periodically they go into tremors, their blood pressure shoots up to 210/110 and stays there. Their heart rate goes to 130-140s. Their temp spikes to 103.
A) Bolus them appropriately in regards to their condition with the medication they're already being given with sedation, seeing as you don't want them to stroke out.
B) Call the doctor. Wait for the doctor to return your call. Wait for the doctor to give you an order for medication that's five times less than what you would give them. Give them that medication. Wait for it to not work. Call the doctor again. Wash, rinse, repeat.
One's legal. The other's not. (One, if discovered, is likely to get you fired.) But which one means your patient doesn't die? And which one means that you're not in trouble for letting them die? Because there was some way you should have been able to express yourself more eloquently over the phone to the doctor, to tell them, "This is a Big Deal. I've been doing this for years. I am not kidding. Please help me to help this person not die."
If that patient died, you could bet there'd be an inquiry. And yes, while you could chart, "MD refused to give more medication," repeatedly, that's cold comfort after someone's died.
Collaborative practice is a bitch, especially when you're at a teaching hospital that gets new doctors every four months.
(1) Replace situation with "crawling out of bed, going to lose the tube that is the only thing keeping them breathing" or "is physically violent with nursing staff, until staff gets injured." Repeat.