This expression expresses an action that was done but was unnecessary. It was a waste of time.
- You needn't have compounded that medication for the patient. They are already taking it.
- We needn't have come so early. The pharmacy class starts in 45 minutes.
- I needn't have brought your medical equipment today. The clinic is closed.
Although this expression is similar to didn't need to~, there is a small difference. We use didn't need to when we are simply saying that it was not necessary (whether or not it was done).
- I needn't have given the bandage to the patient. The patient's wound had stopped bleeding.
- It stopped bleeding, so I didn't need to give the bandage.
- The doctor didn't need to check her email because I didn't send her any. (I don't know if she checked your email or not.)
- The doctor needn't have checked her email because I didn't send her any. (I know she checked your email. She wasted her time.)
- Dr. Lee didn't need to schedule a dental cleaning as she just went a month ago. (I don't know if she made an appointment or not.)
- Dr. Lee needn't have scheduled a dental cleaning as the she just went a month ago. (I know she made an appointment, and she wasted her time.)
- He didn't need to ask if there was any space in the hospital. Every room was full because of epidemic. (I don't know if he asked.)
- He needn't have asked if there was any space in the hospital. Every room was full because of the epidemic. (I know he asked, and it was a waste of time.)
Exercise
Using what you have learned about needn't + perfect infinitive, complete the activity.