Fortunately, nobody has jurisdiction over your brain. They can ask you to reveal the password but they have no way to extracit it from your head. You can always claim you forgot it.
[0]: https://en.wikipedia.org/wiki/Regulation_of_Investigatory_Po...
[1]: https://www.newstatesman.com/blogs/the-staggers/2010/10/poli...
Disclaimer: UK resident who is NOT qualified in law ;-)
More importantly these are the Gardai not the PSNI -- despite the source being the BBC which may have thrown you off.
I wouldn't be too sure of that. I recall reading about some experiments where by monitoring brain activity the researchers could fairly reliably tell if a person shown a photo of a place had been to that place before.
I can't think of a way to adapt that to extracting a passcode or password, but it does suggest that the head is not as safe a storage place as we might have thought.
Isaac Asimov had some mystery short stories set in a future where there was a machine that could probe a mind and extract any information the subject knew, but there was a very small chance that a probing would drive the person incurably insane.
The way they balanced the right of privacy and the need to protect people from crime was to only allow any given person to be involuntarily probed once in their life. Of course this led to many criminals trying to arrange so that they would get involuntarily probed either over something they were actually innocent of or over something they did but that did not have too long a sentence. The criminals recognized that for really serious crimes juries would be reluctant to convict without probe evidence, so once you were probed you could take your criminal career much more safely to the next level.
Just make sure that your device doesn't contain information incriminating other people who the government are trying to track down. That means not using real names, or metadata that connects pseudonyms with physical identities (e.g. phone numbers).