You use diktat to refer to something such as a law or government which people have to obey even if they do not agree with it, especially one which seems unfair.
[disapproval]
diktat in British English
(ˈdɪktɑːt)
noun
1.
a decree or settlement imposed, esp by a ruler or a victorious nation
2.
a dogmatic statement
Word origin
German: dictation, from Latin dictātum, from dictāre to dictate
diktat in American English
(dɪkˈtɑt; ˈdɪkˌtɑt)
noun
an authoritarian decree, order, or policy
Word origin
Ger
Examples of 'diktat' in a sentence
diktat
Result, a combination of editorial diktat and police street closures which had kept the hordes of Gideon at a distant prowl.
Anthony Masters CASCADES - THE DAY OF THE DEAD (2001)