Infidelity investigations often rely on surveillance techniques to gather evidence that can either prove or disprove claims of infidelity. Private investigators use discreet covert surveillance methods, such as monitoring a subject's movements through public spaces or capturing photographic or video evidence, to build a case. Surveillance can include GPS tracking (when legally permissible), and digital monitoring to observe a person's interactions and behavior patterns. The goal is to collect objective evidence, such as photos or videos, to confirm or refute suspicions of infidelity. However, it is crucial that all investigations are conducted in strict adherence to the law no matter the country or state.

Ensuring that privacy rights are respected, and that no illegal methods, such as unauthorized hacking or trespassing, are used. This adherence to legal standards is fundamental to ensuring that any evidence gathered can be used in a court of law if necessary.