What is the determining factor in classifying a border security technology as requiring adherence to the Electronic Communications Privacy Act (ECPA)?

The determining factor is whether the technology is used to intentionally intercept the contents of electronic communications, such as emails, phone calls, or text messages. If a border security technology is designed to capture and review the actual content of private communications, then it falls under the purview of ECPA and must comply with its requirements, including obtaining a warrant in many circumstances. Technologies that only collect metadata (like phone numbers dialed or email addresses) or are used for surveillance without intercepting content (like cameras or sensors) may not be subject to ECPA, although they might be governed by other privacy laws. The key is the purposeful acquisition of the substance, purport, or meaning of a communication.