I know what you’re thinking — only 75%? Come on, man — if you’re gonna snoop, then snoop.  All right, some of you may be thinking that Barack Obama recently promised, “We don’t have a domestic spying program,” but what would one call a program that tracks three-quarters of all domestic Internet traffic and holds the e-mail content between US citizens?

Are we back to parsing the definition of is?

The National Security Agency—which possesses only limited legal authority to spy on U.S. citizens—has built a surveillance network that covers more Americans’ Internet communications than officials have publicly disclosed, current and former officials say.

The system has the capacity to reach roughly 75% of all U.S. Internet traffic in the hunt for foreign intelligence, including a wide array of communications by foreigners and Americans. In some cases, it retains the written content of emails sent between citizens within the U.S. and also filters domestic phone calls made with Internet technology, these people say.

The NSA’s filtering, carried out with telecom companies, is designed to look for communications that either originate or end abroad, or are entirely foreign but happen to be passing through the U.S. But officials say the system’s broad reach makes it more likely that purely domestic communications will be incidentally intercepted and collected in the hunt for foreign ones.

“We don’t have a domestic spying program,” Obama promised — but the NSA’s listening devices aren’t off-shore:

This filtering takes place at more than a dozen locations at major Internet junctions in the U.S., officials say. Previously, any NSA filtering of this kind was largely believed to be happening near points where undersea or other foreign cables enter the country.

“We don’t have a domestic spying program,” but we don’t mind collecting the content of entirely domestic e-mails, emphasis mine:

The NSA is focused on collecting foreign intelligence, but the streams of data it monitors include both foreign and domestic communications. Inevitably, officials say, some U.S. Internet communications are scanned and intercepted, including both “metadata” about communications, such as the “to” and “from” lines in an email, and the contents of the communications themselves.

Much, but not all, of the data is discarded, meaning some communications between Americans are stored in the NSA’s databases, officials say. Some lawmakers and civil libertarians say that, given the volumes of data NSA is examining, privacy protections are insufficient.

“We don’t have a –” — well, never mind.  According to the WSJ and its sources, the telecoms themselves decide what is “responsive” to NSA requests, and at least one provider will only return data involving connections outside the US.  The NSA often presses for domestic intercepts, though, and although providers will argue over the scope, many of them comply.

So what are the checks on this that keep the NSA from conducting a domestic spying program?  Obama insisted that the program has tight oversight “from all three branches of government,” but a former telecom executive says that’s just an illusion:

Paul Kouroupas, a former executive at Global Crossing Ltd. and other telecom companies responsible for security and government affairs, says the checks and balances in the NSA programs depend on telecommunications companies and the government policing the system themselves. “There’s technically and physically nothing preventing a much broader surveillance,” he says.

The effectiveness of the oversight — from the legislative branch, at least — was demonstrated when the Washington Post reported on an internal NSA audit showing thousands of privacy violations a year.  Dianne Feinstein, who chairs the Senate Intelligence Committee, only found out about it when she read the paper.

This program may be a necessary defense against terrorism, but if so, it requires a lot more oversight than it has now.  Furthermore, we need an accounting of what exactly we have prevented through the domestic surveillance conducted by the NSA while eroding the constitutional rights to privacy of American citizens as a trade-off. Without that data, we need to move NSA back to its original mission of foreign signals intercepts, and end the domestic spying program that is coming more and more into focus.