Sure. That's true of most areas of law. All things being equal, the candidate with higher grades will win out. That's especially true if you're looking at going into an area where your personality and things like the ability to source work matter even less.
But gaining experience through extracurriculars and clinics, etc. will be a big help in getting some of these jobs, and I can say that some people working in niche areas like constitutional or human rights law were not necessarily honours graduates in my class.