This is a tough one. Law school is all about reading (tons of it) and writing, and a lot of the reading contains very complicated language and ideas which I would think you would need to be fluent in English to understand. But a 172 on the LSAT means you must understand English pretty well.
If you understand English better than you speak it or write it, I wouldn't worry too much. I don't think any professor is going to downgrade a non-native speaker for grammar and spelling errors, but they will downgrade you if you don't get the ideas, and/or can't get your own ideas across in writing. Why don't you get hold of a Contracts or Property book from a US law school and try reading it, to see how well you understand? Good luck!