Legal Question in Landlord & Tenant Law in Illinois

There has to be a reasonable procedure to determine liability and support their claim. As to a "burden of proof" there is no statutory rule for private rules like these. Instead if there is a battle you could wind up in court for a "declaratory judgment" that the rule is unreasonable and the right to enforce it should be enjoined. If what you're saying is true, however, that the bylaws (part of the actual condo declaration) allows for dogs, a rule enacted only by the board, or even 4/6ths of the owners, can not undo that without a formal amendment. Rather, the remedy for a nuisance rule is the right to evict the owner/occupant from possession, just as it would in case someone was blasting their sound system too loud. I would start with the Board president and get a read on what the real issue is here; it you're "innocent" there may be other issues at stake: does anyone have a unit on the market in this lousy economy? Worst case is that the Association should have an attorney, and while the attorney represents the board you can still suggest that the rule may contravene the declaration and should have been an amendment -- but beware that for which you ask -- a 4/6ths = 66.66 percent. It may be the declaration requires 75% to amend or it may require only the 66.66 (assuming all units have the same % of ownership for voting purposes), and then next step could be a costly amendment that bans dogs. Unfortunately this is one of the major problems with self-managed buildings - without proper guidance the associations can often do things that seem like they're ok but technically violate the Condo Act or even the Illinois not-for-profit corporation laws (if your association is incorporated).