As it is already known, eCollars are currently banned under the guidelines of City Parks and Animal Services. As eCollars are used for (discomforting to painful) punishments to dogs, it makes sense. However, there are still Choke chains and Prong collars allowed in Public Off-Leash Parks. Besides posing a risk to other dogs who can still get their lower jaw caught in these collars (they have NO quick release mechanisms) they also pose a risk to humans who may have to break up two dogs from fighting; these risks include avulsions, punctures or severe lacerations. Off Leash Parks are not a place for these instruments.
Other Scientific information:
The primary use of these is to cause discomfort (at best) to pain (at worst) to control behaviour (Operant conditioning) and can cause side effects such as increased aggression because of the pain they cause (Classical Conditioning). There are far better methods of training and management that are current and far more humane.