In 1987 the Supreme Court ruled that it's okay to increase taxes retroactively and recently L.A. played this card in an attempt to funnel more funds from business owners to help fix the financial crisis in L.A. Not so unexpectedly, much of this news was missing from the more popular main stream media venues.
After several business owners moved out of L.A. and many more teamed up to speak out against retroactive tax increases, L.A. city Council decided to re-evaluate this descision.
In researching this I was surprised to learn that this is nothing new. Retroactive taxes have been a hot topic off and on an within various jurisdictions. The thought that you and I could be taxed as a result of increasing taxes for the year 2008 despite it being the year 2010 (or later) is one of the biggest loads of crap I have ever seen.
The Constitution itself bars ex post facto laws. Since 1798, the Supreme Court has said that limit applies only to criminal laws, not civil measures.
Therein lies the crux of the problem. Cities are not government agencies, they are set up as for-profit corporations and their aim is the same aim as any other business; to earn money. When was the last time Wal-Mart sent you a bill for something you paid for 2 years ago. Or when was the last time Wal-Mart gave you a ticket and demanded you appear in a Wal-Mart court to defend yourself and pay a fine? City statutes are rules agreed upon between two parties in agreement, city statutes and ordinances are not "laws", they are tenets used to define the rules of a business and you are not subject to them unless you agree in contract.