The most startling clause is this: The 451 status code is optional; clients cannot rely upon its use. It is possible that certain legal authorities may w

The most startling clause is this: The 451 status code is optional; clients cannot rely upon its use. It is possible that certain legal authorities may wish to avoid transparency, and not only demand the restriction of access to certain resources, but also avoid disclosing that the demand was made. It seems this clause, as highlighted by deepblueocean in his "TCP Evil Bit" comment, is what is most disturbing... Shouldn't it be made mandatory? Can it be made mandatory?