Wednesday morning the United States Court of Appeals for the Ninth Circuit in San Francisco will hear arguments from the U.S. government regarding a lower courts ruling on the controversial National Security Letters (NSLs).

The Electronic Frontier Foundation (EFF) is asking the appeals court to uphold a ruling that found the NSL provision of the Patriot Act to be unconstitutional. NSLs are a tool used by the government to force telecommunication companies to give customer information without the use of a warrant from a judge. The NSLs are typically issued by the FBI to gather information from companies when related to national-security investigations. This information can include customer names, addresses, phone and internet records, and banking and credit statements.

The most contentious part of the tool is the use of gag orders. When a credit reporting agency, telecom company, bank or travel firm receive the letters requesting customer information they are legally gagged and cannot alert anyone about the incident. Not the customer. Not their families. The individual can seek help from a lawyer but the lawyer then also becomes gagged.

Another worrisome feature of the NSLs are the fact that a judge is not needed to approve the letter or the gag order.

This situation has created a dangerous environment where opportunities for corruption are abundant.  At least one telecom has chosen to fight, however. In 2013 the unnamed company took their NSL to court to debate the constitutionality. U.S. District Judge Susan Illston in San Francisco ruled that the NSLs violated the First Amendment by removing the recipients ability to speak about the letter. Neither the EFF or the company itself can reveal their name. They face federal prison if they do so.

Whatever decisions is made by the appeals court will have huge implications for the way the FBI operates. The case is likely to end up being settled in the Supreme Court.