I would suggest being supportive of and encouraging of your child's wishes to not do homework rather than re-enforcing the coercive maneuvering of their school system to force them to do things they don't want. With regards to homework specifically, researcher Alfie Kohn has shown that there's never been a single study performed proving the effectiveness of homework in improving learning. We've simply assumed it's good for the child and we are forcing them.
There is a huge problem in our education system with forcing kids to do things they don't want. Don't join the bad side - come to the light. Using force and coercion with our children is a horrible approach to teaching.