Born on April 15, 1759, in County Kerry, Ireland, Magill read law.
He was a deputy state's attorney in Frederick County, Virginia starting in 1789.
[1] Magill was nominated by President John Adams on February 25, 1801, to a seat on the United States Circuit Court for the Fourth Circuit vacated by Judge Philip Barton Key.
He was confirmed by the United States Senate on February 26, 1801, and received his commission on March 3, 1801.
[1] Following his departure from the federal bench, Magill resumed private practice in Winchester from 1802 to 1804.