[ucajuzac] Collecting information only for your benefit

We worry of big entities collecting data about you and using it to hurt you.  However, most of this, in principle, can be mitigated with contracts and subsequent market forces: enter into a contract saying the data collected about you can only be used for such and such, with civil penalties for breaking the contract.  And, in principle, contracts are beneficial to both parties.  What modifications to the law and additional technology, if any, are needed to enable writing and enforcing such contracts?

The big exception is The State collecting data about you, whether directly collecting through surveillance or obtaining it indirectly by subpoena, and using it to hurt you, for example in unjust selective prosecution.  The original collector of the data can follow the contract, using the data only to benefit you, and take appropriate care to avoid hackers getting hold of it, but it cannot refuse a subpoena.  Even now, in practice, we generally do not fear the original collector of your data using it to hurt you; we fear someone else obtaining your data.

Can we modify laws such that the government has far less power to obtain data about you through subpoena?  Perhaps, one can only subpoena information that would have been collected and collectible using 1789 technology, when the Constitution was ratified, similar to how they interpret the Constitution by Original Intent.  This kind of modification to the law -- freedom from meddling by the state -- is necessary to encourage a data based economy.