[15] In 2022, Petersen sponsored SB 1138, which prohibited healthcare providers from performing gender-affirming surgeries for minors, including procedures to modify chest appearance to align with gender identity.

[17] U.S. District Court Judge Jennifer Zipps ordered Petersen and House Speaker Ben Toma to produce emails related to the law's passage and submit to questioning, ruling they had waived legislative privilege by voluntarily joining the lawsuit.

[18] In May 2024, Petersen, along with House Speaker Ben Toma and the Arizona Trucking Association, filed two lawsuits challenging the Environmental Protection Agency's new vehicle emissions standards in the U.S. Court of Appeals for the District of Columbia.

"[19] Petersen argued the rules would increase consumer costs and strain the power grid, while EPA Administrator Michael Regan defended them as necessary measures to address climate change and improve air quality.

The state's Democratic officials, including Attorney General Kris Mayes, had opposed reinstating the requirements, arguing it would be "destabilizing" so close to the November election.

[22] As Senate President in 2024, Petersen led Republican legislative efforts to bypass Democratic Governor Katie Hobbs's vetoes through increased use of ballot referrals.

[24] As Senate President, Petersen took legal action to challenge the designation, filing a lawsuit along with then-House Speaker Ben Toma, State Treasurer Kimberly Yee, and several local governments.

[25] The lawsuit argued that Biden lacked the authority to create the monument under the Antiquities Act and claimed the designation would harm state and local communities by permanently barring uranium mining and complicating land development.

In February 2025, he sent a letter to U.S. Secretary of the Interior Doug Burgum requesting a meeting to discuss ending what he termed "government overreach" and the ban on uranium mining in the area.

"[29] The review, which involved a hand recount of nearly 2.1 million ballots, concluded in September 2021 and confirmed Joe Biden's victory in Maricopa County, finding he had actually won by approximately 260 more votes than officially recorded.

[28] Later revealed communications showed that Cyber Ninjas' CEO Doug Logan had acknowledged not knowing Arizona election law when hired, and that contractors struggled with basic ballot counting procedures.

[29] In 2022, the Arizona Supreme Court unanimously ruled that Petersen and other Senate officials could withhold approximately 1,000 emails, text messages, and other communications related to the review under legislative privilege.

[30] The review, which cost significantly more than the Senate's initial $150,000 contract with Cyber Ninjas, was largely funded by external groups supporting baseless claims of election fraud.

[28] Documents later revealed that the contractors had extensive communications with individuals involved in efforts to overturn the 2020 election results, including some who were later indicted in Arizona's fake elector scheme.