If something, for example a political institution, serves only to make a false appearance that that institution exists (for example, courts or legislatures that are heavily dependent on the head of state's will in undemocratic countries), what do you call it? I thought I could use the words 'decorative' or 'decoration', but Lexico doesn't seem to support that view.
-kangaroo court: "a court that ignores recognized standards of law or justice and often carries little or no official standing in the territory within which it resides, or it may ignore due process and come to a predetermined conclusion"
-puppet state/puppet government: a state/government that is legally independent but really dependent on another power e.g. the dictator or a colonial power
In general the term puppet can be used in front of most institutions.