Short answers, pulled from the story.
A law exists in a state of constitutional status when it aligns with the rules set forth in an applicable constitution. This alignment determines whether that statute is acceptable or unacceptable under the nation's highest legal document.
The United Kingdom and New Zealand operate without codified constitutions that laws must conform to. In those nations, no court holds the authority to strike down legislation based on such documents.
Swiss voters retain a remedy through plebiscites to void federal legislation by petitioning for a direct vote. Courts lack the power to void federal laws despite having a written constitution.
Courts determine if legislative acts conflict with constitutional mandates to declare them void in whole or in part. Depending on the type of legal system, any court might rule on validity or only special constitutional courts hold that authority.
National constitutions typically apply only to government actions rather than private citizens. Only governments can then violate the nation's constitution under standard interpretations.