The only story bigger than Paul McCartney jamming with Bruce Springsteen at Hard Rock Calling over the weekend was the way their set ended: with their microphones being shut off before they were finished. But according to festival organizers, their hands were tied -- it all came down to the local curfew.

E Street Band guitarist Steven Van Zandt led the grousing on Twitter, quipping, "Is there just too much fun in the world? We would have been off by 11 if we'd done one more. On a Saturday night! Who were we disturbing?"

He may have a point, but Live Nation pointed the finger at the law in a press release, saying, "It was unfortunate that the three-hour-plus performance by Bruce Springsteen was stopped right at the very end, but the curfew is laid down by the authorities in the interest of the public's health and safety. Road closures around Hyde Park are put in place at specific times to make sure everyone can exit the area in safety."

You'd think McCartney would have been able to issue a decree from the stage or something -- isn't that "Sir" in front of Sir Paul good for anything? -- but apparently not. Perhaps if they'd been playing 'God Save the Queen'?