unconstitutionality; unconstitutional
Refers to the state of being against the constitution, or an act/law that violates constitutional principles. Common in legal, political, and news discourse.
The law was ruled unconstitutional.
Judicial review of constitutionality is an important role of the court.
The court ruled that the law was unconstitutional.
The citizens' group argued that this policy was unconstitutional.
It has been pointed out that the ordinance may be unconstitutional.
違憲 specifically means a violation of the constitution, whereas 違法 is the broader term for breaking any law or regulation.
Compound of 違 (い, 'to differ, violate') and 憲 (けん, 'constitution, law'). The reading いけん is the standard on'yomi combination.