If that ever happens to you then document on a Blockchain that you have first-hand knowledge that someone has committed a crime against you, specifically 18 U.S. Code § 242. By not reporting a crime like that you could leave your fellow Americans exposed to a criminal by leaving that criminal undocumented. But, be very careful as in doing so you are liable for your spoken or written utterances.
18 U.S. Code § 242 - Deprivation of rights under color of law
Whoever, under color of any law, statute, ordinance, regulation, or custom, willfully subjects any person in any State, Territory, Commonwealth, Possession, or District to the deprivation of any rights, privileges, or immunities secured or protected by the Constitution or laws of the United States, or to different punishments, pains, or penalties, on account of such person being an alien, or by reason of his color, or race, than are prescribed for the punishment of citizens, shall be fined under this title or imprisoned not more than one year, or both [..]
https://www.law.cornell.edu/uscode/text/18/242> If that ever happens to you then document on a Blockchain
?? just any random blockchain? In what way does that help? Also, how? Are you buying small batches of bitcoin to spell a message out using morse code or something? Or is this an Etherium contract that does...?
... why the blockchain? And which one? That seems a needless techno-complication, especially if you're trying to spread this advice wide.
> document on a Blockchain that you have first-hand knowledge that someone has committed a crime against you
Farting into a wind is about as effective with the difference of being free.
If someone wants to actually fight this, a dash cam streaming somewhere offsite and secure (cloud is fine) is a million times more effective. It provides direct, court-admissible proof of the claim in a way a personal diary entry, in a notebook or on a blockchain, never could. Barring that, an audio recording on your phone. (Would check your state and local laws first, however.)