Brian Hackler joined Cornerstone in November 2020 as lead of the firm's flagship office in Oklahoma City. He spent over a decade working for Sen. Jim Inhofe (R-OK). The last five years he served as his Deputy Chief of Staff and State Director. In this role, Brian managed and directed staff in Oklahoma City, Tulsa, Enid, and McAlester. Prior to this role, Brian served as a field representative for Sen. Inhofe covering Southwest Oklahoma. As a field representative, Brian gave legislative updates to local communities and helped constituents navigate federal issues.

Before joining Sen. Inhofe's office, Brian served in the United States Marine Corps from 2003 to 2007, where he played a key role in developing and carrying out daily strategic operations, including combat patrols, safeguarding government facilities and gathering intelligence. Brian was deployed to Iraq in 2004 and 2005, where he successfully contributed to the training and organization of Coalition Iraqi forces.

Brian also serves on the Board of Trustees for the Oklahoma City National Memorial & Museum. He currently resides in Edmond, Oklahoma with his wife and four children. He received a Juris Doctorate from the Oklahoma City University School of Law and a Bachelor of Arts degree in philosophy from the University of Central Oklahoma.