"I appreciate that, and here's why: Judges are risk adverse, and inherently conservative, not necessarily politically, but legally," said Cardozo. "If a canary was published on a daily basis, [the party requesting the warrant] might run to court and say, 'The world is going to fall apart if we don't compel them to lie.'
"Judges don't like ruling quickly, but they might panic and agree," Cardozo continued. "In Apple's case, a judge will have months to do this, and it will be fully briefed in the light of day."
But Cardozo noticed, as have others, that Apple did not create a canary for Section 702 of the Foreign Intelligence Surveillance Act (FISA), which is believed to be one of the keystones of the National Security Agency's (NSA) PRISM data-gathering program.
"The silence speaks volumes," said Cardozo, adding that in the absence of a canary there, it's safe to assume that Apple has been served with a Section 702 request.
Apple's report can be found on its website ( download PDF).
Sign up for CIO Asia eNewsletters.