What is meant by the term 'tail' in a surveillance context?

In the context of surveillance, the term 'tail' refers to the practice of conducting an unobserved close watch on an individual. This means that a private investigator or surveillance operative discreetly follows or monitors a subject to gather information without the subject being aware of that monitoring. The effectiveness of a tail lies in its ability to capture real-time behaviors and actions of the individual in question, which can be vital for investigations related to insurance fraud, infidelity, or other civil and criminal matters.

The other options relate to different concepts: a formal legal document pertains to legal processes, subrogation refers to the right of an insurer to pursue a third party for recovery of costs, and providing false testimony is associated with legal proceedings rather than surveillance practices. Understanding the term 'tail' is essential for those in the field of private investigation, as it is a fundamental technique used to gather evidence discreetly.