Yesterday Alaska became the fourth state to legalize marijuana for recreational use. With 74 percent of precincts reporting, 52 percent of voters favored legalization. Alaska joins Oregon and Washington, D.C., which legalized marijuana on the same day, and Colorado and Washington state, where voters approved legalization in 2012.

Alaska has taken a unique approach to marijuana since 1975, when the Alaska Supreme Court decided that the state constitution's privacy clause allows people to possess small amounts of cannabis at home for personal use without fear of arrest or punishment. But that ruling raised an obvious question: Where are people supposed to get the pot they are allowed to use?

Measure 2 answers that question with a system similar to Colorado's. It allows adults 21 or older to possess up to an ounce of marijuana at a time, grow up to six plants at home, and transfer up to an ounce at a time to other adults "without remuneration." It authorizes state-licensed growers, cannabis product manufacturers, and retailers, to be regulated by Alaska's Alcoholic Beverage Control Board or a separate agency created by the state legislature.

Alaska's tax will be $50 per ounce, collected from growers. From the government's perspective, the advantage of that approach, which is similar to the way alcohol is taxed (by volume), is that proceeds from a given quantity of marijuana remain the same as prices drop, which is what will happen as the market develops unless something goes terribly wrong. The disadvantage, from a social engineer's perspective, is that a tax based on weight does not take potency into account (unlike alcohol taxes, which fall more heavily on liquor than on beer). In fact, a weight tax might encourage higher potency, especially as it becomes a larger and larger component of the retail price. If production costs fall as expected, Alaska's weight tax could amount to a rate of 100 percent or more within a few years, giving consumers an even bigger incentive to buy the strongest pot they can find.

Measure 2 prohibits marijuana consumption "in public," making it "a violation punishable by a fine of up to $100." The initiative does not define "in public," but that language probably will prevent people from legally consuming marijuana in any setting other than their homes. As in Colorado, the effort to keep cannabis consumption hidden will make enjoying the newly legal product especially problematic for visitors.

Like Oregon's initiative, Alaska's does not change the state's DUID rules. Under current law, blood test results can be used as evidence that someone was driving "while under the influence of" marijuana, but they are not necessarily conclusive. Alaska does not have a "per se" standard like Washington's, which makes drivers automatically guilty of DUID when the amount of THC in their blood exceeds a specified level.

Update: With 94 percent of precincts reporting, the vote breakdown for Measure 2 remains essentially the same: 52 percent in favor, 48 percent against.