Thanks for the replies, everyone. I obviously shouldn't count on legalization for my defense. It's my understanding that in Ohio the driver is responsible for all contraband in the car unless another party claims responsibility, so "it's not mine" won't fly, either. How about the paraphernalia itself - is it lab tested for marijuana, or is the testimony of the officer sufficient?
Obviously the search was legally problematic to say the least, and my first priority will be demonstrating that.