Typically, no written contracts, nondisclosure agreements, or employee agreements are made with crowdworkers. The clearance process requires a background investigation and the signing of a nondisclosure agreement. The constitutionality of such nondisclosure provisions has been repeatedly challenged. Upon termination from a particular compartment, the employee again signs the nondisclosure agreement. Moreover, a recipient of the NSL may still challenge the nondisclosure provision in federal court. Nonetheless, the recipient of the NSL may still challenge the nondisclosure provision in federal court. The action challenged the constitutionality of NSLs, specifically the nondisclosure provision. Speculations persisted of incompatibility, abuse, an illicit affair, or even nondisclosure of a prior marriage. The nondisclosure provision the government could include in an NSL was also weakened. Ultimately, the "classifiable" aspect of the government nondisclosure policies was dropped. The law has a list of five exceptions for nondisclosure. Rates of nondisclosure vary widely in reported studies.