Even if you take it to court, the statute that authorizes judicial review of NSLs restricts the authority of the judicial branch to engage in judicial review. I

Even if you take it to court, the statute that authorizes judicial review of NSLs restricts the authority of the judicial branch to engage in judicial review. Instead of being able to strike down NSLs for any reason that a court may determine is unlawful, under the statute courts may only overturn gag orders if the court finds “that there is no reason to believe that disclosure may endanger national security of the United States, interfere with a criminal counterterrorism, or counterintelligence investigation, interfere with diplomatic relations, or endanger the life or physical safety of any person. So no you cannot always just take it to court. In many cases it may be illegal to do so.