Contract applies only where monitoring is necessary for the employer's side of the contract, which is hard to envisage (a contract clause announcing CCTV for productivity is not enough). Legal obligation needs a common law or statutory duty (not a contractual one) that the employer can point to by provision or reliable guidance, such as drivers' hours rules requiring tachograph data, with no more collected than the duty needs. Vital interests is confined to life-or-death situations such as a test pilot's physiological monitoring. Public task needs the task to be clearly grounded in law, and cannot be used where a less intrusive way achieves the same purpose.
This control maps to 1 controls across 1 other frameworks. If you already hold one of them, the evidence you collected for it is the starting point here rather than new work.
Every mapping shown was judged rather than inferred from wording similarity, and the ones that failed review are published too. See the coverage reports and what was rejected.
The graph holds this control, the 1 it maps to, and the evidence behind each claim, over MCP and REST.