John was born and raised in Kansas City, Missouri. After graduating from Rockhurst High School, he attended the United States Military Academy at West Point, New York. In the Spring of 1989, John was commissioned as an infantry officer in the United States Army. After successfully completing officer basic course, Airborne School, and Ranger training, John served two years with the 1st Battalion, 506th Infantry Regiment (Currahee) at Camp Greaves on the DMZ in the Republic of Korea. John returned to the United States in 1992, and the Army selected him to serve with the prestigious "Old Guard" at Arlington National Cemetery.
In 1994, John resigned his Army commission so he could go to law school. John attended DePaul University College of Law in Chicago, Illinois. While there, John's criminal law and criminal procedure professor selected him to act as a research and writing assistant. Licensed under a special Illinois statute to practice law as a student, John also clerked at the Cook County State's Attorney's Office--first on the Arson Task Force and then in the Gang Prosecution Unit. As a student clerk, John participated in trials based upon charges of murder and aggravated arson. After graduating from law school in 1998, John turned down a position as an assistant state's attorney in order to return to Kansas City.
In Kansas City, Judge John R. O'Malley of the Circuit Court of Jackson County, Missouri, hired John to serve as his law clerk. John then worked in the Jackson County Prosecutor's Office. As an assistant prosecuting attorney, John gained significant trial experience. John left the prosecutor's office in 2002 to take a job as an associate with the civil litigation firm Horn, Aylward & Bandy, LLC, where he primarily defended health care professionals, trucking companies, and a multi-state convenience store chain. As a civil attorney, John was a finalist for the 2003 Thomas J. Conway Award, which the Kansas City Metropolitan Bar Association uses to recognize attorneys who zealously represent their clients and at the same time maintain respectful relationships with their adversaries.
In March 2005, John opened the doors of The Gromowsky Law Firm, LLC, where he continues to put his real word and legal experience to work for people charged in federal and state courts with crimes such as murder, assault, drug distribution, drug possession, fraud, stealing, and white collar offenses.
As a criminal defense lawyer, John is licensed to practice in courts in Missouri and Kansas.