Landlords are challenging San Francisco's latest move to discourage evictions from rent-controlled apartments, an ordinance requiring them to pay displaced tenants the difference between their current rent and the amount needed to rent a similar unit at market rates for two years. In a suit to be filed Thursday in federal court, property owners and the San Francisco Apartment Association, which represents landlords, say the city's law is an unconstitutional interference with property rights and an unreasonable burden on a landlord's right under the state's Ellis Act to get out of the rental business. 'Permanent landlords'"The city is essentially forcing people to become permanent landlords by making it wildly expensive to withdraw a unit from the rental market and take possession of their own property," said attorney J.