Today, the US Supreme Court summarily struck down Montana’s law shielding its elections from the influence of corporate cash. The court’s 5–4 decision in American Tradition Partnership v. Bullock significantly expands the scope and reach of the Citizens United ruling by striking down state limits on corporate spending in state and local elections.

“The question presented in this case is whether the holding of Citizens United applies to the Montana state law,” the majority wrote. “There can be no serious doubt that it does.” What this means, as John Nichols explains, is that if Exxon Mobil wants to spend $10 million to support a favored candidate in a state legislative or city council race that might decide whether the corporation is regulated, or whether it gets new drilling rights, it can.

What to do? “The court leaves us no choice but to continue to fight for stronger campaign finance laws to prevent corruption,” said Craig Holman, government affairs lobbyist with Public Citizen. “We will do this at the congressional level, at administrative agencies and in the states, as well as work to overturn Citizens United by amending the US Constitution.” Public Citizens’ Democracy Is For People project aims to arm a citizens army with the tools it needs to limit the corrosive impact of money in politics. Find out how to plug into the movement and then share this info with friends, family and your Twitter and Facebook communities.

Writing last week, Katrina vanden Heuvel surveyed the Resolutions Week campaign in which city and town councils and state legislatures pushed for a constitutional amendment to overturn Citizens United. This movement will only grow stronger in the wake of today’s Montana decision.

This video, produced by the Story of Stuff collective, offers an invaluable primer on why the Supreme Court’s closely divided Citizens United decision is incompatible with basic notions of democratic governance.

A weekly guide to meaningful action, this blog connects readers with resources to channel the outrage so many feel after reading about abuses of power and privilege. Far from a comprehensive digest of all worthy groups working on behalf of the social good, Take Action seeks to shine a bright light on one concrete step that Nation readers can take each week. To broaden the conversation, we’ll publish a weekly follow-up post detailing the response and featuring additional campaigns and initiatives that we hope readers will check out. Toward that end, please use the comments field to give us ideas. With your help, we can make real change.