State law which says that landlords have the right to evict tenants in order to "go out of business" short of selling to another landlord. All units in the building must be cleared of all tenants- no one can be singled out.
The Ellis Act "was adopted by the California Legislature in 1985 after the California Supreme Court ruled that landlords do not have the right to evict tenants to go out of the business of being a landlord".