Abstract: Reefer madness is sweeping the nation. Despite a federal ban on marijuana, states have begun to legalize medical and, increasingly, recreational use of the drug. As more states legalize marijuana, their non-legalizing neighbors have seen a distinct uptick in marijuana possession and use—and an attendant increase in crime and accidents. In December 2014, Nebraska and Oklahoma, non-legalizing states that border Colorado, a trail-blazer in the full-legalization movement, requested permission to file suit in the U.S. Supreme Court over their neighbor’s lax marijuana controls, which allow cannabis to come into their states. The Supreme Court denied leave to file. In the wake of the Supreme Court’s ruling, the question remains: What can prohibiting states do to protect themselves from cross-boundary spillover? This Article surveys various litigation—and statutory—options and ultimately determines that prohibiting states should, at a minimum, consider enacting laws modeled on Dram Shop Acts, which create liability against those who sell alcohol to already intoxicated people or minors who then injure third-party victims. These revamped “Gram Shop Acts” would create liability against out-of-state marijuana dispensaries that sell to Home State buyers who, while high, injure third parties in the Home State or those who are residents of the Home State. Gram Shop Acts may help prohibiting states shift some of the costs of marijuana legalization back to those states that foster its use by deterring sales to citizens residing in non-legalizing states and by providing compensation to third-party victims.