The reality is that the federal government has neither the resources nor the political will to undertake sole -- or even primary -- enforcement responsibility for low level marijuana offenses in California. Well over 95% of all marijuana arrests in this country are made by state and local law enforcement. The federal government may criminalize marijuana, but it can't force states to do so, and it can't require states to enforce federal law.

Holder from his letter, obtained by the AP and not available yet online:

"We will vigorously enforce the CSA against those individuals and organizations that possess, manufacture or distribute marijuana for recreational use, even if such activities are permitted under state law," Holder wrote. Legalizing marijuana would be a "significant impediment" to the federal government's effort to target drug traffickers and would "significantly undermine" safety in California communities, the attorney general said.

The Ex-DEA chiefs, in their letter, compared the feds attempt to enjoin Arizona's immigration law and their request to enjoin Prop 19 is not a valid one, according to one law professor, and Holder's comments are more bark than bite:

If Arizona wants to crack down on illegal immigration more strictly than the federal government, the U.S. can act to prevent police in the state from enforcing the law, said Robert Mikos, a Vanderbilt University law professor who studies the conflicts between state and federal marijuana laws.

If California prevents police from enforcing the stricter federal ban on marijuana, the Supreme Court has ruled that the federal government cannot order local law enforcement to act, he said.

I agree with those who say Holder's comments are political posturing and have more bark than bite. California voters who favor Prop 19 should not be deterred from voting.