The National Security Agency has broken privacy rules or overstepped its legal authority thousands of times each year since Congress granted the agency broad new powers in 2008, according to an internal audit and other top-secret documents. Most of the infractions involve unauthorized surveillance of Americans or foreign intelligence targets in the United States, both of which are restricted by statute and executive order. They range from significant violations of law to typographical errors that resulted in unintended interception of U.S. e-mails and telephone calls. The documents, provided earlier this summer to The Washington Post by former NSA contractor Edward Snowden, include a level of detail and analysis that is not routinely shared with Congress or the special court that oversees surveillance. In one of the documents, agency personnel are instructed to remove details and substitute more generic language in reports to the Justice Department and the Office of the Director of National Intelligence. In one instance, the NSA decided that it need not report the unintended surveillance of Americans. The NSA audit obtained by The Post, dated May 2012, counted 2,776 incidents in the preceding 12 months of unauthorized collection, storage, access to or distribution of legally protected communications. Many involved failures of due diligence or violations of standard operating procedure. The most serious incidents included a violation of a court order and unauthorized use of data about more than 3,000 Americans and green-card holders.