Earlier quoted context omitted.
Again, I'm no expert, but I do believe the law would be what would stop you. It could be poorly written, but then we should just rewrite it.
Police, in many countries, have already been found to violate the laws protecting surveillance systems that already exist. If a warrant doesn't stop them today, why do you think it will tomorrow?
If police use these systems outside of their intended and legally mandated forms, that must be dealt with. We do need effective police though. We do that with robust surveillance infrastructure for police queries in the database, possible even with a mandatory log of queries as part of discovery.
I don't have to "think" it will stop them, I can utilize the levers of democracy to check them.