When The New York Times announced its pay meter back in March, publisher Arthur Sulzberger, Jr. also announced that — along with the many, many other pores and passages the paper had built into its gate — the Times had built into its new system the ability to open the gate for breaking-news stories that were, essentially, must-reads. “Mr. Sulzberger wanted a flexible system,” the paper reported at the time, “one that would allow the company to adjust the limit on the number of free articles as needed — in the case of a big breaking news event, for example.”

Or, as Sulzberger told Times reporter Jeremy W. Peters:

“Let’s imagine there’s a horrifying story like 9/11 again,” [Sulzberger] said in an interview. “We can — with one hit of a button — turn that meter to zero to allow everyone to read everything they want,” he said. “We’re going to learn. We built a system that is flexible.”

Last night’s news about the death of Osama bin Laden would seem to qualify as one of those big must-read stories. So it’s interesting to note that the Times’ coverage of the news — all of its articles and blog posts — remained behind the paper’s gate last night. And they’ll remain there. “There are no current plans to open up the news and features about Bin Laden for free on NYTimes.com,” a Times spokesperson told me. “As you know, readers get 20 articles free each month, and they can access Times content through other means, such as blogs, social media and search.”

The Bin Laden story broke on May 1, just a few hours after all non-subscribing Times readers had seen their monthly 20-article count reset to zero. Barring a big Sunday-morning reading binge, most were probably still at the very beginnings of their monthly allotments. And while “any decision to make any content free on NYTimes.com will be made on a case by case basis,” the spokesperson notes, “in this case in particular, the fact that the story broke on May 1 was certainly a factor.”

The Times’ pay meter is probably the most analyzed edifice in the news industry at the moment. And it’s not as if there were nowhere else online (or on television, or in print) to learn about the bin Laden raid.

Still, it’s remarkable how little we know about how the paywall’s breaking-news caveat works. The notion of stories that are so big that they shouldn’t be paid for — or, more accurately, so big that the Times shouldn’t require people to pay for them — is a complicated, but also crucial, one, particularly considering the careful balance the Times has struck between business interest and public interest in its rhetoric about its pay scheme.

If and when a story is taken from outside the wall, who makes the decision about the exemption? Is it someone on the business side or the editorial side— or a collaboration between both? Is the exemption something that the Times will announce publicly, or something it will simply enact, without comment? And if the day of the month on which a story breaks is a factor, as it was in this case…on what day would a big story become exemption-worthy?

The biggest question, though: If Osama’s demise didn’t make the cut, what story would?