As expected, the American Veterinary Medical Association has followed the lead of their expert advisory boards on spay/neuter issues, and issued their own position statement against mandatory spay/neuter laws:
The AVMA does not support regulations or legislation mandating spay/neuter of privately owned, non-shelter dogs and cats. Although spaying and neutering helps control dog and cat populations, mandatory approaches may contribute to pet owners avoiding licensing, rabies vaccination and veterinary care for their pets, and may have other unintended consequences.
The Journal of the American Veterinary Medical Association reported on this in a news article entitled AVMA: Mandatory spay/neuter a bad idea