Hi,

I'd like to know if we are allowed to work (internship in a US law firm) during the LLM. If yes, what are the conditions ? Thanks !

To my knowledge, LLM students are not allowed to work while being a full time student. There is one exception--externship.
Externship must be a credit-granted course (therefore unpaid); it usually requires an application filed in the fall semester and externship work will be conducted in the spring semester. The application process is similar to job hunting, but it should be easier (though still competitive). Not every school provides externship programs; moreover, some externship programs are limited to JDs ,US citizens or citizens of certain specific countries.