When open-Internet advocates wanted to stop the momentum of the controversial Stop Online Piracy Act, they rallied some of the biggest sites on the web to black out their front pages and urge visitors to call Congress.

It worked, creating an Internet-wide freakout that rocked lawmakers on their heels. A lot of people are willing to call their representatives, it turns out, whenever uninterrupted access to cat videos is at risk.

Some organizers of that protest are now hoping to institutionalize the practice of flagging "threats to the Internet" with large-scale actions. Reddit co-founder Alexis Ohanian and the U.S. activist group Fight for the Future are calling this project the Internet Defense League, an initiative to grow a list of website owners willing to use their sites to urge visitors to take action whenever the signal — let's call it a cat signal — goes out to warn against something that may change the structure of the net as we know it.

"The Internet Defense League takes the tactic that killed SOPA & PIPA and turns it into a permanent force for defending the internet, and making it better. Think of it like the internet's Emergency Broadcast System, or its bat signal!" reads the copy on the project's site. "When the internet's in danger and we need millions of people to act, the League will ask its members to broadcast an action. (Say, a prominent message asking everyone to call their elected leaders.) With the combined reach of our websites and social networks, we can be massively more effective than any one organization."

The project's website says: "If you have a website, we'll send you sample alert code to get working in advance. The next time there's an emergency, we'll tell you and send new code. Then it's your decision to pull the trigger."

When netizens get the call about a piece of legislation, the thinking goes, site owners will activate the script, possibly blacking out their front pages or urging visitors to email or call lawmakers.

The legal brains behind the operation are the Electronic Frontier Foundation in San Francisco and Public Knowledge in Washington, D.C, two longtime Internet activist groups. Groups such as theirs and the Center for Democracy and Technology (which isn't listed as part of this initiative) have been analyzing legislation coming out of the U.S. Congress for years and pushing back at what they've deemed to be legislative overreach if they believe the legislation robs individuals of their privacy or freedom of expression online.

"We'll have a community process for vetting actions with the goal of only activating the network for things that are very big deals," says Fight for the Future's Tiffiniy Cheng. "This could get more formal (or formally decentralized) as we go. We want to make this process as open as possible. In addition to talking to other groups interested in Internet Freedom (The EFF, CDT, La Quadrature Du Net,) we currently have a public sub-forum on Reddit, where users can add issues for us to address."

It's the next step in what Cheng says is a broad agenda to support open access to the Internet anywhere in the world. To date, the group's activities have focused on fighting the U.S. entertainment industry's ideas on how to curb Internet piracy both in the United States and abroad. A more recent campaign focused on a controversial piece of legislation in Congress called the Cyber Intelligence Sharing and Protection Act (CISPA). In the wake of the very effective SOPA protests in January, Fight for the Future succeeded in creating buzz around what it was going to do against CISPA, but the results — sites called CongressTMI and Privacy Is Awesome — had nowhere near the impact of their predecessors.

All this suggests that maybe the "cat signal" is an apt symbol. The so-called "Internet community" that came out in force in January was actually a broad coalition of interconnected communities — Wikipedia users, Redditors, free-culture enthusiasts, Internet entrepreneurs and more — each with their own strong personalities and niche interests. Getting such a diverse network to move in unison, even with a compelling message, could fairly be compared to herding cats.

For example: Engine Advocacy, the Silicon Valley group representing investors and entrepreneurs, bowed out of the CISPA debate when the House Intelligence Committee added language that eliminated companies' potential legal liabilities under the legislation. Yet Engine had been one of the groups that flew to DC during the SOPA debate to persuade legislators what a bad idea their bill would be for the innovation economy.

Similarly, perhaps because of its own cybersecurity woes, Google has been silent about CISPA — which passed the House despite threat of veto from the Obama administration — while it was heavily involved against SOPA/PIPA.

Meanwhile, the entertainment industry and other proponents of CISPA have complained that EFF and Fight for the Future lean towards hyperbole and exaggeration in search of rhetoric strong enough to activate their networks.

Cheng retorts that in the face of waxing importance for Internet business and the still-strong influence of the entertainment industry on Capitol Hill, the everyday netizen has to either speak out loudly or be shut out of the conversation about the future of the Internet.

"The content industry gives some of the biggest money to Washington, and has expected ridiculously lopsided laws to come from that," she says. "So it's not that the content industry has talked past the tech industry — they haven't really tried to talk at all."

She adds that the group's primary focus is on users, and not a voice for the tech industry.

"When Facebook has a multi-billion IPO, it's easy to forget that the users make that site valuable. The same goes for Twitter, YouTube, Tumblr, and even Google. We want to make sure that the Internet users don't get silenced once the tech industry has its own version of the [Motion Picture Association of America.]"

The immensely popular cat-meme generator the Cheezburger Network and Imgur have both declared an affiliation with the Internet Defense League, as has Craig Newmark. And the group says that more names will be added soon.

But the group proposes to build a far broader coalition, one that by definition depends on Internet citizenry to respond to a call rather than individual corporate interests. The plan, after all, hinges on the effectiveness of the cat signal that features playfully across the Internet Defense League's front page. And getting cats to cooperate in any predictable way, as many cat-owning Internet users often explain, is a lot harder than it looks.