The phrase "proof of mandate" is correct and can be used in written English.
It typically refers to documentation that provides evidence of authority, permission, appointment, or authorization to act on another's behalf. For example, "The corporation had all of the necessary proof of mandate to take over the subsidiary."
"ISIS put all its chips on creating a state and taking territory as proof of its divine mandate.
"Any time we have overwhelming proof of doping, our mandate is to initiate the case through the process and see it to conclusion as was done in this case".
Like those regimes, whether fascist or communist, China's leaders have sought to transform public space and sporting events into visible proof of their fitness and mandate to rule.
On the other hand, advances in certifying and marking cut diamonds, along with new laws in many countries that mandate proof of origin to discourage "blood diamonds" from countries with civil conflict, have made it harder to fence the most valuable polished stones, says Chaim Even-Zohar, an industry analyst based in Israel.
The U.S. Food and Drug Administration recently mandated proof of CV safety as a major requirement for the approval of new hypoglycemic drugs (32).
Proof-of-concept clinical study.
Often, researchers bypass them and test in vivo effects of drugs loaded in DDS characterized only with a variable degree of scrutiny in vitro, betting that observation of a desired effect exceeding that of "untargeted drug" provides a mandate to publish "proof of concept" papers.
In your letter you wrote, "That people should be legally required to show proof of citizenship is similar to the antebellum mandate that black people produce 'free papers' proving themselves not to be slaves".
Arguably the most important legal issue in the Tea Party today is the individual mandate, which they view as proof of government grown too big and too invasive of individual rights.
New York and New Jersey, which imposed community rating and guaranteed issue without a mandate to be insured, are living proof of that assertion.
The new rules include stricter residency requirements for noncitizens, require team managers to have more detailed paperwork documenting their players' eligibility and mandate that more authoritative birth records be presented as proof of age.
