"The public has a right to know whether the FBI is forcing law enforcement agencies to keep information on invasive surveillance technology a secret."

“such an extensive prohibition on disclosure of information to the court .. . prevents the court from exercising its fundamental duties under the Constitution.” 

Read more:

https://www.aclu.org/news/privacy-technology/surreal-stingray-secrecy-uncovering-the-fbis-surveillance-tech-secrecy-agreements