Barto sponsored a bill to prohibit cities and counties in Arizona from banning plastic bags. SB1241, the "ban on banning bags", became law when the governor signed it on April 13, 2015. In 2019, Barto sponsored three bills relating to childhood vaccination. HB2470 would add a non-medical religious belief exemption for childhood vaccines, and removed a signature requirement for parents. HB2471 would require doctors to inform parents about potential risks of vaccines and how to file for injury claims related to vaccines. HB2472 would require doctors to offer a blood test prior to vaccination; the test would determine if a child already possesses the antibodies that would be developed from a vaccine. Barto stated the bills were not intended to promulgate anti-vaccine policy, but rather were about expanding parental freedom and choice. Barto added "We need to look at the data, look at the science and recognize that there's research on both sides", despite warnings by public health officials that the bills would reduce immunization rates in Arizona.
To challenge House District 7 incumbent Republican Representatives Ray Barnes and David Smith, Barto ran in the four-way September 12, 2006 Republican Primary; Barto placed first with 7,218 votes and Representative Barnes placed second; in the five-way November 7, 2006 General election, Barto took the first seat with 29,952 votes and Representative Barnes took the second seat ahead of Democratic nominees Marilyn Fox, Jeanne Lunn, and Libertarian candidate Jim Iannuzo, who had run for a House seat in 2004. † Won nomination for general election
2008: State Representative – District No. 7
Barto, Republican Representative Barnes, Democratic nominee Jeanne Lunn, and Libertarian candidate Jim Iannuzo were unopposed for their September 2, 2008 primaries, setting up a rematch; in the four-way November 4, 2008 General election, Barto took the first seat with 46,854 votes and Representative Barnes took the second seat ahead of Democratic nominee Jeanne Lunn and Libertarian candidate Jim Iannuzo.
2010: State Senator – District No. 7
When Republican Senator Jim Waring ran for Phoenix City Council and left the Senate District 7 seat open, Barto and Representative Barnes both ran in the four-way August 24, 2010 Republican Primary, where Barto placed first with 10,475 votes ; in the November 2, 2010 General election, winning with 41,849 votes against Democratic nominee Eric Shelley. † Won nomination for general election
2012: State Senator – District No. 15
Redistricted to District 15, Barto was unopposed for the August 28, 2012 Republican Primary, winning with 19,162 votes, and won the November 6, 2012 General election with 58,283 votes against Libertarian nominee Dennis Grenier.
2014: State Senator – District No. 15
Barto defeated David Ryan in the primary, then ran unopposed in the general election. † Won nomination for general election
2016: State Senator – District No. 15
Barto ran unopposed in the primary, then defeated the Democratic candidate, Tonya MacBeth, in the general election.
2018: State Representative – District No. 15
Barto and John Allen ran unopposed in the primary, then both defeated the Democratic candidates, Julie Gunnigle and Jennifer Samuels, in the general election.
