Which situation best exemplifies the principle of judicial review?

Judicial review refers to the power of courts to examine the actions of the legislative and executive branches of government and determine whether those actions are consistent with the constitution. When a law is overturned based on constitutional grounds, it shows the court's role in interpreting the constitution and ensuring that other government actions comply with it. This principle empowers the judiciary to act as a check on the powers of the other branches, safeguarding the constitution as the supreme law of the land.

In this case, overturning a law due to constitutional issues illustrates how the judiciary can protect individual rights and uphold constitutional principles against legislative overreach or executive actions that may violate the constitution. This process reflects the fundamental balance of power within the government and the judiciary's essential function in maintaining constitutional integrity.

The other scenarios do not accurately reflect this principle: a ruling contradicting state law may simply reflect the application of state law as intended, a decision made by popular vote does not involve constitutional interpretation, and a government policy enacted by executive order might not involve a judicial review process at all unless legally challenged.