except for some countries, the right to privacy is also written in the constitution, which would require changing said constitution, which is probably a lot harder than just implementing a law.

I can't say what it takes in every country, but in Denmark the procedure is as follows :

- The proposed change must pass a vote in parliament.

- There must then be an election to parliament.

- The new parliament must also vote in favor of the proposed change.

- Finally a popular vote must pass with at least 40% of all eligble voters voting for it. If less than 40% of eligble voters vote (regardless of where they cast their vote), the proposition fails.

It probably goes without saying that changing the Danish constitution is not a task taken lightly. The Danish constitution also explicitly forbids giving up soverenity.