It’s buried in the middle pages of the foreign pages, well beneath the fold, with no more than a few lines, but it’s a story that tells you why, on domestic issues at least, the Obama administration is living up to the hope that it would bring about change.

“High minded on dope” as the Herald Sun put it, in their cute way — the story being that the Obama administration has directed federal prosecutors not to go after marijuana users in states which have laws allowing medicinal supply of cannabis.

That’s 14 states, including California, and tens of millions of people, who won’t live in the ridiculous situation of two unresolved laws — a state one, allowing cannabis use for alleviation of pain, and side-effects of other medications, in diseases like glaucoma, MS, cancer, and a dozen others — and a federal one, which banned cannabis as a major drug.

There was never any question which law took precedence — a federal criminal law overrides a state law, and many of the US’s libertarians (with the honourable exception of Ron Paul) went kinda quiet when a defence of states’ rights came up in this matter.

But enforcement and priorities is a matter purely for the executive, which can let a law go dead if they want. The biggest example of that hitherto was the Comstock Act, which had forbidden the transmission of “obscene” material by the mails. Though flagrantly unconstitutional, it was on the books for decades, sometimes enforced, sometimes relaxed, depending upon the administration.

Obama’s instruction to discontinue active prosecution of marijuana users in medical-marijuana states transforms the US overnight, from a country with one of the harshest antidope regimes, to one with (in some areas) some of the most liberal in the world.

For both genuine and bogus users of medical marijuana alike, the federal law was onerous by being capricious. Caprice is something a few libertarian fair-weather friends of the rule of law don’t seem to care much about, but it’s crucial to a genuinely minimal legal framework. The Feds couldn’t prosecute more than a small fraction of dope users, but they could swoop at any time.

Since prosecution includes forfeiture of property, the legal grey area had a counter-effect — the strait-laced old people with cancer and glaucoma who would benefit from medical dope were often too frightened to use it, while the chancers willing to take risks for a cheap high were lining up at the clinics with fake scripts.

Deferring a federal law to local standards puts the onus on states to sort out how porous their medical marijuana regimes are going to be. That may well mean that some clinics are raided by state cops — but they will have to have probable cause (Law and Order 101: run a full US legal case relying only on knowledge gleaned from the popular TV franchise) of something other than marijuana use per se.

Of course that doesn’t apply to the 36 states where the drug remains illegal tout court. There the crime and punishment mill will continue: open a private prison in a town from which manufacturing has long departed, staff it with locals who have an interest in keeping it filled — often with former workmates, who went the other way (they can be seen in any episode of Cops, being pulled over, shirtless). The sheer amount of illegal drug use in the US is the greatest disproof of the deterrent effect of long sentences — in this area of the law at least.

In jurisdictions across the world, dope gets you a fine, a warning, community service after repeated offences. In the US it can get you five years, if you get a bad judge, a bad lawyer and bad luck. Property forfeiture has created local rackets, whereby cops and prosecutors buy confiscated houses at government auctions for a song, and then put them back on the market at commercial prices.

Some on the US libertarian right are welcoming the move by Obama. Others like the National Review are grizzling about non-enforcement of law (rule: the right will always grizzle about whichever branch of govt they don’t control, going from “unelected judges” to “populist legislators” to “unchecked executive”, like an invalid turning in bed).

But these are the small things that make big changes that make Obama’s election worthwhile. Would President Hillary Clinton have made a similar move? I doubt it. Notwithstanding the need to keep hammering at his imperial foreign policy, in US domestic politics the line between progress and regress is as clear and sharp as the edge of a cigarette paper.