The Drug Enforcement Administration raided two medical marijuana dispensaries in California yesterday. The agency is now refusing to disclose any details of the raid. This is all part of a strategy that dates back to at least 2009. It goes like this: With permission from the U.S. Attorney's office, the DEA raids a dispensary, seizing marijuana but also cash and electronics; it makes no arrests, but asks a judge to seal every document pertaining to the operation and refuses to talk about it with the press. This has two effects: It implies that an investigation is ongoing (even if it's not); more perniciously, it makes it difficult to learn where and how often these raids are happening.