Marijuana prosecution appears to be a political mandate

This is truly unbelievable…

SAN FRANCISCO – Federal prosecutors said today they would retry marijuana grower Ed Rosenthal on cultivation charges, even after a federal judge urged them to drop the case and chastised the government for lodging charges solely to punish the self-proclaimed “guru of ganja.”
U.S. District Court Judge Charles Breyer demanded to know who in the Department of Justice made the decision to continue pursuing Rosenthal, who had his original conviction overturned last year.
Rosenthal can’t be sentenced to prison even if he is convicted because the 9th U.S. Circuit Court of Appeals upheld the one-day prison sentence ordered by Breyer in 2003.
Newly appointed U.S. Attorney Scott Schools made the decision, said Assistant U.S. Attorney George Bevan, but he was not sure if Department of Justice officials in Washington were involved.
The judge said the government’s position to go forward left him no choice but to hold a trial, which he scheduled for May 14.
“This isn’t a criminal case, this is a political case,” said Rosenthal, who appeared in court dressed in a blue wizard’s robe with a golden marijuana leaf emblazoned over the breast. “I may as well get my money’s worth and have a trial.”

Newly appointed U.S. Attorney. Interesting.
Scott Schools replaces US Attorney Kevin Ryan (who prosecuted Rosenthal for the past 4 years) and claims to be only a temporary replacement. Ryan (one of the infamous group of US Attorneys who was fired) was supposedly actually fired for incompetence (and it was Schools who “investigated” Ryan). Schools appears to be a political hack, with some history of politically motivated prosecution.
And now Schools is doing this.
So what is going on here? What possible reason is there to prosecute Rosenthal other than to make the federal government look even more stupid? Has their fear of what we can do to their precious drug war so colored their judgment? Is there a strategy here that I’m missing?
Update: Digby picks up on it, and the comments in that thread are a pleasant sight.