Million-member Internet activism group Demand Progress is gearing up for a day of activism on Monday in concert with the Supreme Court’s hearing of the Kirtsaeng v John Wiley & Sons case.

This vastly under-reported case has tremendous implications for millions of Americans and could undermine our ability to use sites like Ebay and Craigslist — or even hold old-fashioned garage sales. Monday presents a key opportunity to make sure more people know about the case, and put pressure on Congress before Big Business and their brigade of lobbyists convince lawmakers to side against the interests of average Americans and wrest from us the ability to resell things we’ve purchased if they happen to have been manufactured abroad, in whole or in part.

Demand Progress runs the website YouveBeenOwned.org, which more than 100,000 people have used to email their lawmakers in support of the First Sale Doctrine’s application to all products — the notion that Americans should be able to resell the things they own.

Via said site, Demand Progress is urging Internet users to post ribbons and ball-and-chain icons on their websites on Monday to alert their visitors to the Kirtsaeng case and its implications, and to encourage them to contact Congress — as of Thursday morning, more than 2,000 sites had signed up to do so.

The case pits public interest groups and retailers against manufacturers, Hollywood, publishers, and the recording industry, as SCOTUS decides if we have the right to resell many of the things we own, from books to iPods to our cars and homes: The Court will determine if and how the First Sale Doctrine applies to products made abroad.

There’s something viscerally wrong about losing the ability to resell things that you own — and dare I say, un-American;. But it’s easy to make a progressive case in support of the First Sale Doctrine: If manufacturers hold more rights over products the make abroad, that increases the incentive to off-shore, which is bad for labor and the environment. Undoing or limiting the First Sale Doctrine would undermine reuse and recycling efforts and make it harder to build any sort of alternative, local, less-consumerist, less growth-based economy.

No matter how the Court rules, activists expect to fight a legislative battle come winter, as the losing party is likely to push legislation to reverse the Court’s decision.