A law is deemed unconstitutional when it conflicts with the principles and provisions outlined in a constitution, rendering it invalid. Judicial reviews conducted by courts, particularly supreme courts, assess whether laws comply with constitutional standards. When a law is ruled unconstitutional, it can lead to nullification and removal from the legal framework, reinforcing the supremacy of the constitution. This process safeguards individual rights and liberties and upholds the rule of law, ensuring that all governmental actions adhere to constitutional mandates.