"Maybe we should come back tomorrow and try this," I thought. Sitting in the inner sanctum of America's highest court, in a chamber never before made visible to the world in video or even color photographs, I struggled to summon the courage to do what I had come to: stand and interrupt the supreme court.

As I waited that February morning, listening to oral arguments about an obscure patent law case and taking in the room around me - the high, ornate ceiling, the giant red curtains and marble figures towering above the bench - the reality and gravity of the institution I had entered intruded into my thoughts.

I didn't want to have to interrupt these people, Ginsburg and Sotomayor and Breyer, their actual presence becoming real as each justice spoke for the first time. I felt the deference that our highest court should deserve from every citizen. Yes, We the People should see the court as ours and the justices as our champions - ensuring that the law is on our side.

Back in the real world of the Roberts court, I focused on the people for whom I was there to stand up, who the court's elitist majority had betrayed, and who I was determined not to let down. Finally, my cue came, and with a quick count of 1-2-3, I stood to speak. "I rise on behalf of the vast majority of the American people," I declared in a brief protest captured on unprecedented video, "who believe that money is not speech, that corporations are not people, and that our democracy should not be for sale to the highest bidder."

Then came this morning. We just learned that despite a steadily growing national outcry in response to its disastrous Citizens United ruling in 2010, the radical corporatist majority of our supreme court is willfully deaf to this popular democratic alarm. The Roberts-led majority, with its ruling today in McCutcheon v FEC, is determined to continue its assault on the last shreds of egalitarian restraint on the dominance of big money in our politics.

As Stephen Breyer writes in his dissent, today's decision "undermines, perhaps devastates, what remains of campaign finance reform." American law, he says, is now "incapable of dealing with the grave problems of democratic legitimacy".

Justice Breyer is right. This is very bad news. But let's be honest: the court's 5-4 decision - to strike down aggregate limits on the total amount of money billionaires can spend to buy political power from candidates and parties - should come as no surprise.

I glimpsed a small sign of this deeply elitist contempt for political equality when I rose to disrupt the court's session that day. In the 15 seconds that I spoke, before security grabbed me and pulled me from the chamber, I didn't notice much beyond the shifting of people around me and onrushing security - but I did see Justice Antonin "I don't think $3.5m is a heck of a lot of money" Scalia lean back and faintly smirk.

Yes, we all should have seen this shameful decision coming. And I'm no legal expert, but any American should need exactly zero scholarly explanation to see it for exactly what it is: Citizens United 2.0 – a "floodgate", as Breyer put it, now opened for potentially billions more dollars from a tiny slice of the wealthiest 1% of Americans to drown our democracy.

In its complex argument, the Roberts majority states that "the possibility that an individual who spends large sums may garner 'influence over or access to' elected officials or political parties" is not a problem of corruption. But when members of Congress spend 30-70% of their time raising money from a fraction of the 1%, when billionaires and corporations can spend millions of dollars – often undisclosed – to empower or destroy candidates for office, the simple truth is this: the big-money corruption of our political system is so profound that we can no longer seriously claim to be a functional democratic republic.

We celebrate the principle of political equality, of "one person, one vote". But the new rule is "one dollar, one vote", and it is a recipe for plutocracy. This was essentially true before Citizens United, painfully obvious after, and now, in McCutcheon's wake, it is beyond rational argument. For a nation riven by historic economic disparity, with a generation poised to be the first to fall behind its parents, the loss of real democratic power for the vast majority of citizens is an existential crisis.

What can we do? To start, we can stand up and say No.

Some have said to me that disrupting the court - or any activism targeting it - serves only to harden the elitist majority's stance. Perhaps. But there comes a time when we can no longer just defer to the institutions governing us, when the failure of those institutions demands that we stand up as citizens and take nonviolent action – no matter the cost.

With a supreme court hellbent on enabling rather than preventing corruption, a corrupt Congress possessed of a lower public approval rating than King George in the time of the revolution, and a president unable or unwilling to challenge that corruption, now is such a time. I stood up, spoke out, and went to jail for this cause. I did so with little expectation that it would move the court but with hope that it would inspire the voices of people who believe that our votes – not the unprecedented power of unlimited dollars from billionaires and corporations – should determine our common future.

Indeed, one man's action is far from enough. But like the abolitionists, the suffragists and the civil rights workers who defended and extended democracy before us, we can use the power of nonviolent civil resistance on a massive scale to win the central democratic fight of our time: passing Constitutional and legislative reform that separates wealth and state, banishes big money from our politics, and puts our government firmly and solely in the hands of the People.

Today, when the supreme court has judged a billionaire's money to be his inviolable political voice, let's answer with a commitment to make our voices impossible to ignore.