PhD

He did his PhD in/on criminal law.

I think "in" is correct here, but I'm not entirely convinced "on" would be wrong. What do you think?

Thanks.

I tend to agree, but feel "in" is used for the general area, whereas "on" is used for the specific topic.

Jasmin165 said:

He did his PhD in/on criminal law.

I think "in" is correct here, but I'm not entirely convinced "on" would be wrong. What do you think?

Thanks.

Click to expand...

"In" is correct. You do a degree (or similar) IN a subject. As part of his PhD he probably wrote several papers ON different topics, but he gained his degree IN criminal law.

But when you write a thesis, it is so in-depth and specific that it is on a narrow topic.