Germany's blanket data retention law is illegal, EU top court says

There is no codified legal process for a US state to leave the Union, and the only previous attempt caused a civil war

A member of the EU has both an implicit right to withdraw from the treaties (deriving from international customary law around treaties) and an explicit legal path to follow. A process which they control in their entirety (as in they can't be forced to stay longer than they wish by the other countries and can't be forced to leave earlier than the prescribed deadline)

For instance, the 1974 French SAFARI scandal,

where the government wanted to build a centralized computer database that would collect country-wide administrative data, starting with the 400 (physical) police files, and IIRC with a single social security number for each citizen,

has caused such an uproar that the project was abandoned and the data privacy regulator CNIL was soon created.

(Note the totalitarianism (aka "high modernism") inherent in computers, by the way what they show tends to be accepted as truth, the way they don't have any common sense, the way their digital nature tends to classify people into strict categories, which then become set in stone by their limited capacity to forget, the way the free flow of information turns qualitative and how they give a lot of power to the State while democracies try to limit this power.)

Sadly, we've recently seen its failure - caused in a big way by it being stripped of its power in 2004, leaving only a consultative (non-)power - in 2010 a law about "a general principle of information sharing between administrations" has still been created.

Some notable worries are about the preceding 2007 law that authorized ethnic statistics - while personal data treatment using ethnic or racial data, and adding race and religion values in the administrative files are still forbidden - the potential of ethnic data becoming racial data is still very high.

Another worry is about the genetic prints file : created in 2002 and first limited to sexual criminals, it has since been extended to a whopping 5% of the population, 87% of which have NOT (yet, quite a lot of the debate being how long these files should be kept) been condemned for the reason they got added to the file. It gets worse, and shows how quantitative can become qualitative : because genetic information is NOT independent between family members, a staggering third of the population ends up having its genetic identifiers at least partially stored in these files.

A 2022 project (submission date ending 2 weeks ago) to interconnect the digital prints file with the criminal records file has mentioned a potential future project of connecting both with the generic prints file... (among others) with also a policemen-suggested requirement that "the solution be compatible with remote work [...] not requiring strong authentication".

Member states have agency to leave the EU whenever they'd like if they wish not to be bound by agreed upon laws

In particular, service providers will probably still have to maintain the infrastructure to activate “general and indiscriminate” data retention on demand.