slim – If your scheme has always had that same pet by-law then your scheme has never been a ‘no animal scheme’. Your owners have been mistaken in believing that the animal by-law has been prohibitive.
Instead, your scheme has always had a permissive pet by-law i.e. a by-law been that permits animals based on approval by the owner’s corporation, and with approval not being legally able to be unreasonably with held.
Any owner (or indeed any tenant with an owner’s approval) can apply to keep an animal at your scheme, and if the owner or tenant does not have an animal that has previously caused problems etc then that animal cannot be unreasonably refused by the OC. Approvals are on a case by case basis.
If the owner’s corporation unreasonably with held a pet approval then any affected occupant could take your OC to NCAT, and they would probably win.
Therefore, if I was in your position I would
(a) as soon as possible have the OC ratify a set of acceptable and reasonable conditions for the keeping of an animal (either by the Committee at a Committee Meeting or by amendments to the by-law), and then
(b) at the Committee Meeting resolve to write to the owner and request that the owner formally apply in writing to keep their cat as they are currently in breach of the pet by-law by keeping the cat without approval. Your OC should also provide assurances that approval will not be unreasonably with held by the OC if the cat owner agrees to abide by the conditions for the keeping an animal and does not breach the conditions.
Should your OC wish to formally amend the existing animal by-law to include these conditions then the OC can only do this at a general meeting by the proper processes set out in the Act e.g. a Special Resolution followed by Registration.
Changes to by-laws is a longer process and involves costs e.g. legal costs in the drafting of the by-law, and Registration costs. It would be wise to seek the assistance of a lawyer when wording the amendment to the by-law.
An extra condition that all schemes that I have been involved in have included is that the animal owner must provide a photograph of the animal so that anyone who sees the animal on common property, or sees the animal behaving badly, or ‘lost’, will recognise the animal and know to which owner the animal belongs.