First Amendment?
UK doesn’t have a Constitution or Bill of Rights.
Understood. My point was that the US BoR as expressed in the constitution is not unique as a matter of principle of check against the ruler, and Magna Carta makes our BoR "not first" either
the Bill of Rights (not to mention the constitution it is part of) is unique among governments.
Then there is The Constitution of the Russian Federation, Rights and Freedoms of Man and Citizen
Now, if "unique" means to delve into the exact words used, yes, of course. Any string of 50 or more words is apt to be unique to the author.