Morphine is a controlled substance issued by medical authorities for pain relief.


Ignoring the whole medical-marijuana factor...

Your usage was controlled by the doctor and wasn't illegal.


if you had been using it to party, get high, escape reality etc... then it would be illegal usage.


Mr. Phelps smoking a bong however... no. That was partying. Doctors - at least reputable ones - don't prescribe controlled substances for that.

(note I said "reputable" doctors)