The phrase "law unconstitutional" means that a law goes against or is not allowed by the rules of the country's constitution. It means the law is not permitted or is deemed unacceptable according to the nation's highest law. Full definition
He insisted that declaring laws unconstitutional will not close that gap. (laschoolreport.com)
If a federal district court rules a city or state law unconstitutional, state courts do not have to obey that ruling. (law.stackexchange.com)
The article comes on the heels of the contentious Vergara v. California (2014) verdict, which deemed teacher tenure laws unconstitutional in California. (ascd.org)