[1][3][4] Mehalchick is a graduate of Scranton High School[5] and received a Bachelor of Science degree in geoscience from the Schreyer Honors College of Pennsylvania State University in 1998.

[4][6][7] From 2001 to 2002, Mehalchick served as a law clerk for Judge Trish Corbett on the Lackawanna County Court of Common Pleas.

President Biden nominated her to the seat vacated by Judge John E. Jones III, who retired on August 1, 2021.

[19] During her confirmation hearing, Senators Marsha Blackburn, John Kennedy, Ted Cruz, and Lindsey Graham vigorously cross-examined her over her recommendation that Pennsylvania State University president Graham Spanier's child endangerment conviction be reversed and remanded for a new trial, which was adopted by the District Court, then later overturned by the United States Court of Appeals for the Third Circuit on the ground that the District Court had not correctly determined whether Spanier was entitled to federal habeas corpus relief.

[citation needed] While clerking for Corbett, she began volunteering with Pennsylvania's mock trial education program, which operates in multiple high schools across the commonwealth.

[6] A 2006 newspaper article said she had raised funds for Lawyers in the Classroom and the Northeast Regional Cancer Institute[4] and had volunteered for the Big Brother/Big Sister program, the Boys and Girls Club, and United Neighborhood Centers.