To my knowledge, these days the only times that an autism diagnosis can have legal ramifcations is in custody battles for children, or when trying to join certain careers such as police or army. There may be others, but you'd have to look them up. The ADA protects us from discrimination at work or when receiving services, and the new healthcare laws prohibit insurance companies from denying us coverage based on a pre-existing condition.
The only way you can receive disability-specific benefits such as job support, SSDI, service animals, assisted living, etc. is by having an official diagnosis. If you don't need services, and the entire point of the diagnosis for you is a better understanding of yourself, then it's really up to you whether or not to pursue it. I got diagnosed initially because I just wanted to know for sure if I had it, but it's had a lot of unexpected benefits for me. I wound up getting accommodations at school, joining a social skills group, finding a job coach/support worker, and getting accepted to a government program which sets up people with disabilities with paid internships to gain work experience. It also makes me feel safer knowing that if I ever run into law enforcement and the like, if they get suspicious of my behaviour, I can carry a card explaining my condition, and have the documented proof to back it up. My diagnosis also had the benefit of making my family understand me a little better and accept my quirks a little more. They're not 100% there yet, but it's an improvement over what it was.
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"Survival is insufficient" - Seven of Nine
Diagnosed with ASD level 1 on the 10th of April, 2014
Rediagnosed with ASD level 2 on the 4th of May, 2019
Thanks to Olympiadis for my fantastic avatar!