[chryuop]

If you know both languages well it can help you. Knowing Japanese and reading the translation from English you can sometimes understand why a phrase meaning nothing is like that (you can recognize a wrong interpretation of の、が、は that can change the meaning).
However, many times the phrase can have a slight change in the translation and if you are not very good at both languages you will miss that small error and take the translation for good.

Just my 2 cents...