The fact that you went to McGill will help - I know that the highly competitive schools in the northeast see a decent number of McGill applicants and know that it is tough to get high grades compared to the big American schools. However, they won't cut you that much slack - just like engineering students, you'll still be expected to have the numbers at the top tier research schools. I don't know how well the smaller schools that you've applied to will know McGill. Maybe you could point out that 3.2 is still a respectable GPA coming from a school like McGill.
http://www.mcgill.ca/law-studies/information/grades
Look at the grade distribution on the charts at the bottom and you can see that the median is 3.1, 80th percentile is 3.3, 90th percentile is 3.4. As I understand it, that is severe grade deflation by American standards (I think even Princeton's median GPA is 3.3, and it's a school commonly described as grade deflated). I would guess your GPA is probably about the 70th percentile.
That 30 isn't helping you out very much though. If it was unusually low compared to your practice tests, maybe consider redoing it. If you can score 34+, it will REALLY help to show that your GPA may not be reflective of your abilities. Of course, do this only if you're VERY SURE you can score 33+. A lower score on the second attempt might sink your application altogether.
