Judicial review gives the courts power to review actions by the legislature, this is a feature in many Democraticnations. Legislative decisions can be declared unconstitutional or unreasonable 
Judicial review in the USA is the process whereby people appeal to the US Supreme Court about a decision by the legislature. It can be local or national. The courts can rule a law unconstitutional. It was the only barrier that kept Dick Cheney from literally taking over the world. That, after all, would have been unconstitutional.