On a Federation starship, there are certain orders that only a captain may give. While
The only person who can countermand or override the captain is the ship's chief medical officer – and once he does so, the captain will lose any power over him until the doctor withdraws his suspension of the captain from duty or an appeal is convened. However, if the captain removes the chief medical officer from duty (as I have done with Khan) first, then the doctor then loses all power over the captain. So each has power over the other, and the one who moves first wins (in the short run, at least).
These are things I must keep in mind, since the current situation is, of necessity, only temporary. A starship needs a doctor, and the Murgatroid is no exception to this rule. She may, in fact, have an even greater need than the average starship in the fleet. This is why our first stop, upon emerging from hiding, has been to visit