Q. A co-op owner purchased her unit in 2005 and has been subleasing it to the same tenant since 2011. The co-op board recently passed an amendment to the bylaws that states that an owner cannot sublease a unit for more than two years, and it applies retroactively. The board is forcing the sublease tenant to vacate in two months, despite having a lease that runs another seven months after that. Does the owner or tenant have rights in this case?

       —Questioning the Board’s Actions

A. “The lease was signed before the new rule went into effect and the tenant and landlord depended on the rules of the co-op at that time,” says attorney Adam Leitman Bailey of the Manhattan firm Adam Leitman Bailey, P.C. “Because this rule is trying to impose a bylaw retroactively, it would be unjust and would not be a basis to annul a contract. This would be similar to the reasoning of the United States Constitution’s ban on ex post facto laws. The co-op would need to sue the shareholder and the tenant in housing court, and I do not predict a successful result.”