In which monitoring cases should a balancing test be carried out?

ANSWER

When the legal basis for processing data in monitoring is Article 6(1)(f) GDPR, i.e. the controller's legitimate interests. Under that provision, processing cannot be based on this ground where the interests or fundamental rights and freedoms of the data subject requiring protection of personal data override the controller's interests. Examining this relationship and determining whether the data subject's interests or fundamental rights and freedoms override the controller's interests is precisely what the balancing test is for.