It would be worth double-checking your local regulations, but tattoos do not generally restrict you from organ donation. You should make sure you get your tattoo from a licensed business, of course.
As far as legal status -- that is a good question. I would think that as long as you updated it at least as often as you update your driver's licence, it would remain a valid indicator of your intent. That might mean adding a date to the tattoo, and adding another one every few years. You might contact your local hospital and see what they would do if they had a fresh corpse with no ID but a organ donor tattoo...
I would think that as long as you updated it at least as often as you update your driver's licence, it would remain a valid indicator of your intent.
Why? Doctors have procedures for how to deal with organ donations. That procedure means looking at driver's license and organ donor cards. There are huge legal risks for them being creative.
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