In a lawsuit filed Wednesday, the cash-poor city of Oakland is trying to make the mighty United States of America stop enforcing its laws against the sale of marijuana. We wondered on what basis the city expects to prevail.

The answer comes from the legal concept estoppel, which in plain English means something like “a promise is a promise.”
The city is arguing that U.S. officials — including President Barack Obama — said they would not stop dispensaries from selling pot if the dispensaries comply with state and local law. So Oakland invested a lot of money and staff time in to setting up a regulatory system for the dispensaries. And now the feds are legally obligated to keep their word and leave these pot sellers alone, Oakland officials say.
“We’re concerned that the government through its action and inaction caused the city to rely on the fact that we could proceed to dedicate the resources that we did to set up this dispensary system,” Oakland City Attorney Parker told us.
On Oct. 19, 2009, U.S. Attorney General Eric Holder announced guidelines that his department would use in enforcing the U.S. laws making marijuana illegal:
As a general matter, pursuit of these priorities should not focus federal resources in your States on individuals whose actions are in clear and unambiguous compliance with existing state laws providing for the medical use of marijuana.
But the government continued to prosecute some cases, and in 2011 began a series of high-profile raids and legal actions against large dispensaries, including some of the best-known marijuana businesses in Oakland.
On March 15, Melinda Haag, U.S. Attorney for Northern California, told KQED’s Michael Montgomery that her office was flooded with complaints about marijuana dispensaries, and that the Oct. 19 memo didn’t mean marijuana that comply with state and local law would not be prosecuted. She said federal agents would focus on marijuana businesses close to schools and other places children gather.