While department officials said they are committed to enforcing federal restrictions on marijuana, prosecutors have now been told not to expend effort on cases unless they fall in one of the eight areas.
The areas include distribution to minors, situations when marijuana revenue is going to other criminal enterprises, trafficking across state lines and growing on public land.
The criteria mean, for example, that federal prosecutors will not charge a marijuana dispensary simply because it is large or profitable, said a Justice Department official who spoke on condition of anonymity.
However, the criteria also stop short of guaranteeing immunity for anyone, leaving business and individuals open to prosecution if the case fits one of the eight areas, the official said.
Colorado and Washington will need to have regulatory systems to protect against those types of crimes, or else risk giving up the whole experiment, the department said in a statement.