Final answer:
A pharmacist may refuse to dispense a controlled substance if it lacks therapeutic value or is not being used for a legitimate medical purpose.
Step-by-step explanation:
A pharmacist may refuse to dispense a controlled substance if he/she determines the medication lacks therapeutic value or is not being used for a legitimate medical purpose. This is known as the pharmacist's professional judgment. It is important for pharmacists to ensure the safe and appropriate use of medications and to prevent misuse or abuse of controlled substances.