Huawei is gearing up for the biggest fight in its 32-year existence. The embattled Chinese telecom company today filed a lawsuit against the U.S. government challenging a section of the 2019 National Defense Authorization Act (NDAA) that bans the U.S. government, its contractors, and suppliers from purchasing Huawei equipment and services.

The lawsuit, which was filed in a federal court in Texas, seeks a permanent injunction against the ban and a declaratory judgement that the restrictions imposed on Huawei via Section 889 of the NDAA are unconstitutional. The law “prevents us from serving our U.S. customers, damages our reputation, and deprives us of opportunities to serve customers outside the United States,” said Guo Ping, the company’s rotating chairman, at a press conference that was streamed live from Huawei’s headquarters in Shenzhen, China. “It is an abuse of the U.S. lawmaking process. This section strips Huawei of its due process, violates the separation of powers principle, breaks U.S. legal traditions, and goes against the very nature of the constitution.”

Guo also accused the U.S. government and Congress of smearing the company and misleading the public about unsubstantiated claims of espionage on the part of the Chinese government. “Even worse, the U.S. government is trying to block us from the 5G market in other countries,” he said. “Restricting Huawei’s contribution to American and other nation’s 5G networks will only harm their national interests.”

Huawei claims to hold more than 2,500 patents critical to 5G and says its technology is years ahead of its competitors.

“The U.S. government has long branded Huawei as a threat. It has hacked our servers and stolen our emails and source code,” Guo said. “Despite this, the U.S. government has never provided any evidence supporting their accusation that Huawei poses a cybersecurity threat.”

“The U.S. congress has repeatedly failed to produce any evidence to support it restrictions on Huawei products,” Guo added. “After exhausting all other means to allay the doubts of some U.S. lawmakers, we are left with no choice but to challenge the law in court. In enacting the NDAA, Congress acted unconstitutionally as judge, jury, and executioner.”

John Suffolk, global cybersecurity and privacy officer at Huawei, underlined the complexities and inherent weaknesses of technology to call out what he considers to be hypocritical accusations being made against Huawei. “Just because you have a name on a box, doesn’t mean that’s what’s in that box comes from that named vendor. Only about 30 percent of what’s in a Huawei box actually comes from Huawei. The rest comes from the global supply chain,” he said during the press conference.

“It’s also true for European telecommunications companies. They have joint ventures with Chinese-owned organizations. They buy parts from Chinese companies. It has a European label on it and that so-called European technology is sold freely around the world and in America,” Suffolk added.

Huawei allows its customers to audit and inspect its technology, but it doesn’t claim to be perfect, Suffolk said. “It’s not to say that we always produce perfect code. It’s not to say that we always execute every process the first time correctly. No organization in the world can say that,” he said

Suffolk and Guo were among a group of six top Huawei executives who took the stage to share prepared comments about the lawsuit. The company says it will defend itself vigorously and that it looks forward to its day in court.

Guo last week went on the offensive during a keynote address at the MWC Barcelona event in Spain. He directly challenged claims that the vendor is using its telecommunications equipment as a tool for the Chinese government to spy on other countries.

“Huawei has not, and we will never plant backdoors, and we will never allow anyone to do so in our equipment,” Guo told attendees.

The U.S. government has led the charge on banning Huawei this past year, and has called on its allies to join them. Some have as both Australia and New Zealand have banned equipment. And some have not. The U.K. last month stated that it did not think Huawei’s equipment was a threat to security; German media reports suggest that Germany will come to a similar conclusion.