SAN FRANCISCO — The scandal surrounding the sudden resignation of an adulterous CIA director has stunned the American public not just for its prominent cast of characters, but also because of the ease with which authorities appeared to have traipsed through personal email accounts. Technology has transformed communications much faster than the law, giving US authorities at all levels the power to routinely search reams of intimate emails, texts and instant messages, with much lower burdens of proof as far as the relevance to a criminal case. Often, the subjects of electronic searches never know that they've been hit, let alone why. Recently, big tech companies including Google Inc and Facebook Inc are pushing back, refusing to disclose even old communications without a warrant and effectively daring the government to press its policy in court. The issue has been thrust into the spotlight by the still-unfolding scandal that started with the revelation that General David Petraeus, while serving as CIA director, had an extramarital affair with his biographer, Paula Broadwell. The relationship was discovered because Jill Kelley, a Tampa socialite and family friend of Petraeus, complained to the FBI's Tampa office about anonymous harassing emails. Kelley herself didn't realize how badly an electronic inquiry could mushroom beyond control. She wrote an email on Wednesday to Tampa Bay's mayor that said her family had been “put through the ringer,” in part because police released 911 phone call transcripts with her home address and cell phone number. That email, in turn, was among those released Friday after public-records requests to city hall from the media. In the initial probe, the FBI was disturbed that Kelley's anonymous emailer had confidential information about Petraeus' whereabouts. It issued an administrative subpoena empowering agents to examine the email accounts from which the messages came, a law enforcement source told Reuters. Investigators learned that the harassing messages were sent to Kelley by Broadwell. The FBI eventually got reams of emails, most likely with a warrant or the consent of the correspondents. The agency declined to comment. In another twist, Marine Gen. John Allen, commander of NATO and US forces in Afghanistan, is now also under investigation for allegedly inappropriate communication with Kelley that was discovered during the course of the same FBI probe. Allen has denied that the two had a sexual relationship, officials said on condition of anonymity. Authorized snooping has quietly but rapidly reached an unprecedented level in the United States, and the disgrace of senior military officials not accused of any crime provides a rare opportunity to reflect on that transformation, privacy rights advocates said. “If they subpoena you for your evidence, you can say `buzz off.' That's why all these are being served on third parties,” said George Washington University law professor Orin Kerr, a former Justice Department trial attorney. “It's hidden information, and the service providers can comply cheaply and easily.” Subpoenas for business records have been commonplace for decades, but as individuals move more of their lives online, the services they adopt are subject to the same scrutiny. — Reuters