BOSTON — John Deaton isn't waiting until November to pick a fight.

The Republican Senate candidate and trial attorney filed an amicus brief this week before the state's highest court, jumping into the legal battle between State Auditor Diana DiZoglio and the legislative leaders who have spent two years blocking the audit Massachusetts voters demanded at the ballot box in 2024.

But Deaton didn't stop there. He also filed a separate taxpayer lawsuit — joined by 27 Massachusetts residents — to force the Legislature to comply with the law voters passed.

His sharpest attack was aimed not at the Legislature, but at Attorney General Andrea Campbell. Deaton argues Campbell is representing the Legislature in fighting the audit while simultaneously deciding whether DiZoglio can hire her own lawyer to fight back.

"That is not a legal system," Deaton said. "That is a protection racket dressed up in constitutional language."

The backdrop is stark. The Legislature that refuses to open its books is the same Legislature that presided over a Medicaid system that paid benefits to the deceased, a State Police overtime scandal that cost taxpayers millions, and procurement failures that enriched politically connected contractors.

"When one party controls every lever of power for decades — the Governor's office, the House, the Senate — and then fights tooth and nail to prevent anyone from looking at the books, the public is entitled to ask why," Deaton said. "What are they afraid the auditors will find?"

Massachusetts voters approved a ballot initiative in 2024 with 71% of the vote, granting State Auditor DiZoglio explicit statutory authority to audit the Legislature. Since then, House Speaker Ronald Mariano and Senate President Karen Spilka have refused to produce documents, defied the Auditor's requests, and hidden behind claims of legislative privilege.

Governor Maura Healey, who campaigned on transparency, has remained silent as her Attorney General has worked to shut down the very audit voters approved.

Deaton's amicus brief argues the Supreme Judicial Court has inherent authority — centuries old and exercised across virtually every American jurisdiction — to appoint independent counsel for DiZoglio. The Attorney General's dual role, he argues, creates an irreconcilable structural conflict that only the court can remedy.

The separate taxpayer lawsuit — Deaton and 27 Massachusetts Taxpayers v. Clerk of the House — is currently pending before a Single Justice of the SJC.

"I filed this brief and I filed this taxpayer lawsuit because someone has to stand up and say: the voters were right, the law is clear, and no amount of procedural gamesmanship by the most powerful people in this state changes either of those facts," Deaton said.

The Beacon Hill fight mirrors the core of his Senate campaign, which calls for term limits, a stock trading ban for members of Congress, and a crackdown on the revolving door between Capitol Hill and K Street.

He graduated magna cum laude from Eastern Michigan University while being treated for testicular cancer in his junior year, then earned his law degree cum laude from New England School of Law in Boston. He joined the Marine Corps along the way, served as a Judge Advocate at Marine Corps Air Station Yuma, and was awarded the Meritorious Service Medal and the Navy Marine Corps Commendation Medal before being medically retired in 2002 after a non-combat injury.

For the last two decades, Deaton has represented mesothelioma and cancer victims against Fortune 100 companies. In 2017, he personally funded independent testing of children's makeup playsets sold by Claire's, confirmed the products were contaminated with asbestos, and triggered an international recall. In 2020, he filed a pro bono amicus brief in the SEC's lawsuit against Ripple Labs, the issuer of the XRP cryptocurrency — ultimately representing more than 75,000 small token holders — and helped hand the agency a landmark partial defeat.

Amicus briefs, in other words, are his signature move. His 2023 memoir Food Stamp Warrior, dedicated to his mother, became an Amazon bestseller within 24 hours of its release.

Deaton ran against Elizabeth Warren in 2024 and lost. He is now challenging Senator Ed Markey, who has held federal office since 1976.