Washington (CNN) As a federal air marshal, Paul Steward has sworn an oath to enforce the law in the skies above America.

But when he's off-duty, the 42-year-old officer has embraced a fringe ideology that rejects the US government's authority to impose many of the country's laws.

The apparent contradiction between Steward's work and his personal views surfaced following what should have been a very minor brush with the law on one of the nation's waterways. The ensuing legal battle led to a suspension from his normal duties for the Transportation Security Administration.

Steward was riding his Sea-Doo watercraft on the Susquehanna River in Maryland in 2018 when a state Department of Natural Resources officer issued him three citations related to his vehicle's registration, according to court documents.

Instead of paying the fines, Steward aggressively fought the citations by espousing beliefs of the so-called "sovereign citizen" movement, court and police records show.

Prosecutors and judges, Steward stated in court filings, were "foreign agents," the court overseeing his case was a "private corporation" controlled by foreign powers and the state of Maryland committed "fraud" by bringing such penalties against him.

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The FBI has described sovereign citizens as "anti-government extremists who claim the federal government is operating outside its jurisdiction" and has previously identified the group as a "domestic threat." The FBI notes that sovereign citizens operate in loosely affiliated networks without established leadership.

On YouTube, dozens of videos depict encounters between law enforcement and so-called sovereign citizens who refuse to cooperate during traffic stops or who contest the legality of court proceedings.

At some point, the TSA was contacted about Steward's behavior.

Steward's attorney Cindy O'Keefe told CNN her client is currently on "restricted duty" and that he has been questioned by the Department of Homeland Security's inspector general about his statements. Steward is assigned to an air marshal field office and maintains a security clearance, she said.

TSA officials referred CNN's questions about Steward to the DHS inspector general. A spokesperson for the inspector general said the office neither confirms nor denies open investigations. Federal air marshals are subject to initial and periodic background investigations, and "misconduct or other disqualifying information identified" may impact an employee's security clearance, according to the TSA.

O'Keefe said the controversy surrounding her client has been blown out of proportion.

"Mr. Steward is not now, nor has he ever been, associated or affiliated with any group, cult, organization or association with any 'sovereign citizen' movement. He does not hold any beliefs or opinions of the so-called sovereign citizen movement," O'Keefe said.

She added that Steward pulled the bulk of his court filings from "templates" found on the Internet as he sought to have the citations dismissed.

But police records and trial transcripts show that Steward's views extended beyond the screeds contained in his court filings.

Many of his comments had a confrontational tone that challenged the authority of those who worked in law enforcement, much like himself.

He warned the officer who issued him the citations that she could be fined more than $500,000 for running his name through police databases, according to a police incident report.

Across one of his citations, he wrote, "I do not consent to these proceedings."

Many of the tactics employed by Steward mirrored those used by sovereign citizens, according to Mark Pitcavage, a senior research fellow at the Anti-Defamation League's Center on Extremism who has tracked the sovereign citizen movement for more than two decades. For example, Pitcavage pointed to the way Steward included a copyright sign next to his signature and referenced obscure provisions of commercial laws.

Pitcavage described the sovereign citizen movement as an ideology that contends the US government has been infiltrated and made illegitimate through an insidious conspiracy. He estimates that the movement has several hundred thousand adherents in the US.

When Steward's case went to trial at a Maryland district court in September 2018, he picked up where his filings left off. He questioned the judge's authority and made statements that didn't appear to make sense under the circumstances.

After Steward learned no prosecutor would be present for the trial, he demanded to know "where is the state? Are they dead? Where is the body, the corpus delicti?"

When the judge noted Steward's not guilty plea, which Steward protested having to enter a plea at all, the air marshal called himself a "flesh and blood man" and said the judge did "not have power of attorney over me."

The officer who wrote the citations testified that Steward told her that she was "not able to give him a lawful order because I was not an agent of common law."

Steward told the judge that officers called him a sovereign citizen during the encounter. "And I said well actually that's an oxymoron because sovereign is to be king of your domain and citizen means you're part of group politics," Steward said. "So it's an oxymoron. I said I'm just a sovereign American trying to stand up for my rights."

The judge found Steward not guilty of two of the three citations but guilty of "operating an unnumbered vessel."

Steward's appeal of the case was rejected, and he ended up paying $88 in fines and fees, according to court records.

Less than a year later, Steward was cited again for not properly registering his water scooter. According to the police report, he "was extremely non-compliant" and "grabbed a camera and started to record the encounter."

Steward initially challenged the citations in court but ultimately agreed to pay fines of about $240, court records show.

One of the officers involved in that case said Steward threatened him during a court appearance, touching his shoulder, smiling and telling him to "be safe," according to another police report.

"I believe Steward was not meaning for myself to be safe but to watch out for him," the officer wrote.

Attorney O'Keefe told CNN that Steward genuinely meant to tell this officer to be safe and was not trying to be threatening.