It’s a month to go before the arrival of the General Data Protection Regulation, or GDPR, when Europeans will gain a significant amount of control over their own data and privacy.

The regulation is a big deal for any company that does business in Europe. If they make a mistake, it could cost them 4% of their worldwide revenue (or 20 million euros).

Generally, the law requires Internet users to be told exactly what their data will be used for, and they then have the choice to say yes or no, without being nudged one particular way, as well as allowing people to have their info purged.

The end result might mean that many companies that have increasingly developed their business models around a powerful database- that they are starting to harness increasingly effectively- may have to think again.