Read: What is Donald Trump hiding?

Other presidents have demanded discretion, too. Since the 1980s, presidents have required key staff to sign a form that mandates protection of information marked as classified. But, again, Trump’s NDAs push the envelope far beyond national security and sensitive policy details to all “nonpublic information.”

How did we get here?

NDAs became common in private industry in the 1970s with the rise of tech companies that sought to protect trade secrets, such as algorithms, product design, and inventions. This kind of protection makes sense. Let’s say a pharmaceutical company is conducting groundbreaking research that could lead to an exclusive new drug. If an employee leaked this secret information, that would cause significant financial harm to the company. NDAs for trade secrets—like other protections for intellectual property—encourage investment in research and development, and allow firms to share confidential information internally without risk of unfair competition by an insider.

Since the 1980s, NDAs have expanded beyond these legitimate goals. More and more employees are asked to sign them—studies shows that more than a third of the U.S. workforce is bound by restrictive covenants—and they cover more and more categories of information and activity. Private companies regularly require their employees to sign contracts that prohibit disclosure of any information that might hurt the company, including misconduct and unethical behavior. As the public has come to learn with the advent of #MeToo, confidentiality clauses are also standard practice in settlements with an employee who is the victim of sexual harassment or discrimination. Rose McGowan and other women spoke up against the now-disgraced producer Harvey Weinstein despite their belief that their silence contracts might expose them to legal liability.

Read: How legal agreements can silence victims of workplace sexual assault

Ultimately, thanks in part to the publicity of the #MeToo campaign, McGowan and others were not sued by Weinstein. And despite NDAs’ prevalence, the law includes many limits on not only their enforceability, but also their use. The courts have been consistent in maintaining that NDAs cannot prevent an employee from reporting illegal conduct and aiding agency investigations. The National Labor Relations Board holds that non-disparagement clauses, as well as clauses that attempt to prevent employees from discussing with their co-workers the terms and conditions of their job, conflict with the rights of workers to engage in concerted activity. The courts have invalidated agreements that prohibit employees from filing charges about harassment and discrimination. The federal Defend Trade Secrets Act (DTSA) includes a whistleblower-immunity clause, and the law requires that every new NDA since the law was passed, in 2016, include a paragraph alerting employees to their whistleblowing rights. Several state and federal bills seek to limit NDAs in harassment settlements.