My understanding is that they are using 1) # of breeding females, and 2) whether or not someone ships pups without the new owners ever being on the premises of the seller, as the 2 criteria to distinguish hobby breeders from commercial breeders.

1) I think the law says 5 females. Does the law consider age of the females? Does the law consider whether the female is spayed or not?

2) Whatever that # is, and however they define it... Does the law say # of breeding females AND shipping pups, or does it say # of breeding females OR shipping ups, or is it an AND/OR?

2) Is there other criteria that would be more effective to be used to distinguish hobby from commercial breeders?

Here's what I found on AKC. It says they want breeders to "self identify". Female # is UNDER 5.

http://www.akc.org/governmentrelations/usda_aphis_faqs.cfm#enforcement