A last-minute change to the National Security Agency reform bill making its way through Congress, as reported by the Guardian on Tuesday afternoon, may minimize one of the greatest dangers of the program. Or it may make things far worse!

At issue is the number of completely innocent Americans who will be subjected to the NSA’s scrutiny under the new, reformed phone dragnet, in which the telecoms retain the data but conduct queries for the NSA. Language added to the USA Freedom Act, which is scheduled for a House floor vote on Thursday, may limit how much of the data on those innocent Americans the NSA can actually keep – and for how long.

To understand the risk going forward, of course, it helps to understand how your phone calls get sucked up right now. But going forward, somebody’s going to have to make it very clear whether it will be the telecoms or the NSA removing numbers from the database. Otherwise you’re still going to be spied on for liking the same kind of pizza as a terrorist.

Inside the ‘corporate store’: how your calls are analyzed now

According to a newly released document obtained by Edward Snowden, the NSA matches newly collected metadata against existing collections to evaluate 'foreign intelligence purpose'. ( via the Intercept

When defenders of the NSA try to make people less worried about its phone dragnet, which currently collects a significant portion of all the phone records in the US, they claim that its massive database isn’t subjected to the NSA’s most advanced computer analysis. “There is no data mining, there’s no powerful algorithms chugging through it, trying to imagine relationships,” former NSA Director Michael Hayden claimed at a debate the other week.

The defenders claim the NSA will never have a way to track your calls to your psychologist, or your secret girlfriend. But that’s only true if your calls don’t get sucked up in one of the queries the NSA runs on people suspected of ties to terrorism.

If they do get sucked up, your calls can be dumped into what is often called the “corporate store” – a database of all the phone dragnet query results, and the nuclear bomb hiding inside the Snowden revelations.

Once your records are in the corporate store, they become subject to what court documents describe as “the full range of [NSA's] analytic tradecraft”. That means the NSA can start checking to see who else you called, using algorithms to try to map out all your relationships – perhaps even tying your phone number to your email and social media identities and tracking those relationships, along with what you search and read online.

In addition, since 2011, the NSA has been permitted to use Americans’ phone numbers to search – and in some cases to access the content of – phone calls they’ve already collected. So, while the phone dragnet doesn’t currently include call content, it can provide a way for the NSA to access the content of your calls.

Worse still, there are few safeguards. While the NSA needs a “foreign intelligence purpose” to start looking at this collected phone numbers, they don’t need to have any basis for suspecting you have ties to terrorism. The NSA doesn’t have to audit these searches, either – they can apparently, under the current program, keep the data forever. That needs to change.

A method to the madness: why your calls get hoovered, too

A watchdog report released in January recommended the NSA possess the same 'reasonable articulable suspicion' in the so-called 'corporate store'. ( via Privacy and Civil Liberties Oversight Board

You may be thinking you have nothing to worry about. Because neither you nor your friends talk to terrorists, right?

But it’s possible to get sucked up without talking to terrorists, via some other common number – a voice-mail dial-in, or a telemarketer, or a pizza place. A Stanford study conducted last year discovered that even among a group of 300 people with almost no mutual ties, over 17% were connected on the second so-called “hop” – or degrees of separation – through T-Mobile’s voice mailbox system, with other common numbers like Comcast and FedEx linking other people on a second hop. In a watchdog report issued earlier this year, the Privacy and Civil Liberties Oversight Board estimated that as many as 120m phone numbers a year may have gotten sucked into the NSA’s analytical maw.

So you may not talk to terrorists, but if you and a suspected terrorist both use FedEx, you still might have your most intimate relationships exposed to NSA’s analysis.

Right now, the NSA tries to minimize the number of innocent people whose call records get sucked up in queries by taking those voicemail and cable provider numbers out of the database … though local pizza joints may be harder to spot.

But it’s unclear what will happen if the phone dragnet reform passes Congress. Will AT&T and Verizon pull out all these numbers for the government? Because if they don’t, an even larger number of innocent Americans will get exposed to NSA’s intrusive analysis than under the current system.

A still-broken process: how will the NSA decide if you’re trouble?

As the Guardian is now reporting, new language in the USA Freedom Act may ensure that even if the NSA gets all these phone records of innocent Americans, they won’t be able to keep them. The bill that passed two committees of Congress and is barreling toward a vote only required the NSA to destroy data they received after five years – and even then, only if it wasn’t related to a terrorism investigation … which all the data, by definition, was, because it had been sucked up!

So the old language basically permitted the NSA to keep whatever it got for as long as it wanted.

The new language would “require the prompt destruction of all call detail records” turned over by the telecoms “that the Government determines are not foreign intelligence information.” At least in theory, this legislation would force the NSA to destroy data if it discovered that it had gotten your phone number because you like the same pizza as a suspected terrorist does.

But in the process, the language actually seems to expand the reasons the NSA can keep your data, beyond a tie to terrorism to include “foreign intelligence information”. If the NSA thinks you have interesting friends and relatives in China or Russia or anywhere else, it might keep your data. If it thinks you have ties to the drug trade, it might keep your data. If you work for an interesting foreign-owned company, it might keep the data.

Plus, what process is the NSA going to use to decide if your phone number – after all, it’s just a number, without a name – is “foreign intelligence information” or not? The NSA has to conduct some seriously intrusive analysis just to determine if your phone number amounts to foreign intelligence information!

So to learn enough about your phone number to decide to destroy it, the NSA probably has to do intrusive searches on your number.

Alas, even if Tuesday’s markup changes represent a breakthrough, Americans may be far too intertwined – both the terrorists and completely innocent pizza fans – to bake in true privacy without more oversight.