How soon is "relatively soon?" The answer is 296 days. That’s how long it took for the Obama Justice Department to respond to the passage of last November’s historic statewide ballot measures in Colorado and Washington authorizing the commercial production and retail sale of cannabis to those over the age of 21.

In a four - page memorandum, issued August 29 by United States Deputy Attorney General James Cole, the administration for the first time provided details regarding its intentions in states that move forward with regulating marijuana. The memo advises the U.S. Attorneys of all 50 states not to interfere with state - compliant legalization schemes or to prosecute those licensed to engage in the plant's production and sale, provided that such persons do not engage in pot sales to minors or divert the product to states that have not legalized its use, among other guidelines.

“In jurisdictions that have enacted laws legalizing marijuana in some form and have also implemented strong and effective regulatory and enforcement systems to control the cultivation, distribution, sale and possession of marijuana, … enactment of state law by state and local law enforcement and regulatory bodies should remain the primary means of addressing marijuana-related activity,” the memo states. It cautions, however, “If state enforcement efforts are not sufficiently robust, … the federal government may seek to challenge the regulatory structure itself in addition to continuing to bring individual enforcement actions.”

Cannabis law reformers welcomed the Justice Department’s directive, though some also expressed skepticism. Their caution is understandable. In a 2009 memo (the Ogden memorandum), the administration pledged not to intervene in medical cannabis states But federal officials reversed course in 2011, issuing an overriding memo (the Cole memorandum) which reaffirmed that state-sponsored activities involving the production and distribution of medical cannabis would continue to be a priority for federal law enforcement officials.

Yet there are indications that things may be different now. Specifically, the latest DOJ memo no longer argues that state-compliant commercial cannabis operations and for - profit ventures are, per se, worthy of federal action. “[P]rosecutors should not consider the size or commercial nature of a marijuana operation alone as a proxy for assessing whether marijuana trafficking implicates the Department’s enforcement priorities,” it says. Further, there now exist more than a dozen states that explicitly license cannabis production and distribution. When the feds issued their 2009 prosecutorial guidelines, only two states, Colorado and New Mexico, specifically imposed regulations governing the plant’s distribution.

Consequently, last week’s memorandum likely has implications that extend far beyond the nascent Colorado and Washington laws governing recreational cannabis use. It arguably provides a green light for newly implemented medical marijuana distribution schemes in Arizona, New Jersey, Maine, Rhode Island, Vermont and Washington, DC -- as well as forthcoming programs in Connecticut, Illinois, Massachusetts, New Hampshire, Oregon and Illinois. (California, unlike the before-mentioned states, has never passed legislation explicitly licensing and regulating medical pot distributors.) The memo also indicates that the federal government may let stand recently enacted state laws -- such as those in Colorado,Kentucky and Vermont -- which permit state regulators to authorize farmers to grow hemp as an agricultural commodity.

However, before exhaling too deeply, marijuana advocates must remember that the Justice Department’s memo indicates a change in federal policy, not a change in federal law. Further, the memo is advisory only; U.S. Attorneys are individually responsible for interpreting the new federal guidelines and how they apply to any cases that they intend to prosecute. With some U.S. Attorneys already pledging to ignore the new policy directive, it is clear that those who remain wedded to federal pot prohibition won’t be going down without a fight.

Paul Armentano is the deputy director of NORML, the National Organization for the Reform of Marijuana Laws, and he is the co-author of the book Marijuana Is Safer: So Why Are We Driving People to Drink?