Ninety cities across California joined LA in asking the state Supreme Court to uphold the unusual fee plan, which earlier had been tossed out by two lower courts. The state Supreme Court's reversal now becomes case law and can be cited in similar cases across the country.

"The fact that almost 100 cities backed LA in this suit tells you that owners are going to find themselves facing even more fees in the months ahead," an attorney who has represented several apartment investors over the years tells GlobeSt.com.

The case (Apartment Assn. of Los Angeles vs. City of Los Angeles) began in 1998, after LA's City Council approved a $1-a-month charge on each unit in a building to help fund the cost of paying for more inspectors. Under the program, the owner of a 75-unit apartment complex would pay $75 a month, or $900 annually, to offset the local government's cost of hiring enough staffers to ensure that every rental in the city is inspected at least once every three years.