Holder has formalized the policy previously mentioned of ending federal drug raids against sick people:

The Obama administration delivered new guidance on medical marijuana to federal prosecutors Monday, signaling a broad policy shift that will mean fewer crackdowns against dispensaries and the people who use them.

Attorney General Eric H. Holder Jr. instructed government lawyers that in 14 states where medical marijuana use is legal, federal prosecutors should focus only on cases involving higher level drug traffickers or people who use the state laws as a cover story.

“It will not be a priority to use federal resources to prosecute patients with serious illnesses or their caregivers who are complying with state laws on medical marijuana, but we will not tolerate drug traffickers who hide behind claims of compliance with state law to mask activities that are clearly illegal,” Holder said. “This balanced policy formalizes a sensible approach that the Department has been following since January: effectively focus our resources on serious drug traffickers while taking into account state and local laws.”

Washington Post: Obama administration issues new policy on medical marijuana