How effective to be a foreign speaking lawyer in USA?

In my opinion an important aspect of a lawyer's job is developing and managing relationships with clients. The client-lawyer relationship often begins with an intake interview where the lawyer gets to know the client personally, discovers the facts of the client's case, clarifies what the client wants to accomplish, shapes the client's expectations as to what actually can be accomplished, begins to develop various claims or defenses, and explains his or her fees to the client....
This article may help:
http://www.llm-guide.com/blog/351/advice-for-foreign-lawyers-coming-to-the-us-to-get-graduate-degrees-both-llm-jd

The language or accent is hardly important, if you are admitted to the Bar.