Getting Historical Bank Statements from AIB?

To clarify a few things - it's not a ruling it's a newspaper article about a particular individual's experience five years before the current legislation was implemented.

There a couple of things you need to keep in mind:

• Businesses including banks cannot continue to hold your data after the period where it is needed for them to conduct business and the penalties are such that most business including the bank have procedures in place to sanitise their files on a regular basis. So you can expect that a bank will only have long term data on products like mortgages and long term loans, documentation on products that have been in dispute for some time and only more recent data on products such as savings & current accounts. Anything else is a bonus.
• And the next thing is that the GDPR legislation is there to protect your data, not to allow you to circumvent the normal fees for obtaining such data. That means that while you are entitled to the data they have on you, there is not obligation on them to recreated and deliver up documents such as statements etc that they no longer have. So it is very possible that all you will get is an unformatted printout of whatever computer records they have.
• Another think to keep in mind is that everyone including the banks are entitled to their legal defence and that could mean that were you to use the data obtain via the GDPR legislation in a court case, where a discover order would normally be required to obtain it, then you leave the door open for the company that delivered up the said to data to argue for it's exclusion from the case if it would normally be refused in such situations. So in such circumstances I'd advise you contact a solicitor before taking such steps.

In my opinion, unless you are very luck or you have been in significant disputes with the bank over the past 25 years, it is very unlikely they will have usable data stretching back over such a period. Good luck and do let us know how you get on.