At common law, certain relationships are characterised as fiduciary relationships and come with certain additional onerous obligations, such as the duty to act in the best interests of the person you are representing, the duty to avoid conflicts of interest, the duty to account for any undisclosed profits, etc.<p>Though perhaps a slight oversimplification, I would say that a guiding principal for determining whether a relationship is characterised as fiduciary one is the possibility of control over another person's affairs, either literally (as in the case of a trustee or agent), or because that person is accustomed to place a high degree of trust in your judgement (attorneys, financial advisors).<p>In that context, I find this article quite interesting (if a little short). Maybe there is a concept emerging of "data fiduciaries", even if regulators and courts don't yet call it that. It has long been accepted that a financial institution that holds your stocks and bonds has onerous obligations not just to their regulators but to you as their principal. Given how important and valuable data is becoming, people may begin to question why data custodianship should be treated any differently.<p>Incidentally, in some European asset-backed finance transactions, I have already seen "data trustees" appointed to hold personal data relating to the underlying assets in accordance with applicable data protection laws.<p>(The specific rules about fiduciaries will vary by jurisdiction, so don't complain if the above is not a perfect description of the rules in your location, though I'd be interested to hear if your rules are fundamentally different.)