The National Association of Criminal Defense Lawyers has released a white paper, “Electronic Surveillance & Government Access to Third Party Records” (NACDL pdf; archive pdf), which includes a discussion of privacy laws, including electronic communications privacy. Here’s information from the introduction:
The past twenty-five years have brought dramatic advances in information and communication technologies, from the birth of the World Wide Web and the widespread use of personal computers, cell phones, personal satellite navigation systems, and other “smart” handheld and tablet electronic communication devices. Such developments have fundamentally altered the way people work, communicate, and socialize, providing a level of convenience, efficiency, and access to information that was previously unimaginable. At the same time, the amount of private information amassed by third parties like Internet service providers (ISPs), email providers, cloud computing services, and cell phone carriers has grown exponentially, creating a culture where this new technology has the potential to invade personal privacy through the creation, collection, and aggregation of such information. Unfortunately, changes in technology have outpaced the law and much of this information is accessible to law enforcement and other government agencies without a warrant based on probable cause.
Federal law governing the privacy of electronic communications has not been meaningfully updated in over twenty-five years and many federal courts have struggled to adapt Fourth Amendment jurisprudence to the realities of the digital age. […]
Since the 1870’s, a warrant has been required to read postal mail, and since the Supreme Court’s decision in Katz v. United States, a warrant has generally been required to wiretap telephone conversations. However, under current law, email, text messages, and other electronic communication content do not receive this same level of protection. Until January 2012, GPS-tracking information was subject to review by law enforcement without any judicial supervision, even though such information may easily reveal associations, affiliations, practices, and preferences – ranging from the intimately personal to the political.
In August 2011, the Executive Committee of the Board of Directors of the National Association of Criminal Defense Lawyers (NACDL) passed a resolution adopting the principle that law enforcement access to the content of private electronic communications and geolocation information should require a warrant supported by probable cause. The Fourth Amendment is the appropriate starting point for assessing the limits on government access to these records, and its guarantees should not turn on the mode of communication, nor can they favor one medium over another.