[1] Giles was admitted to the bar and entered private practice in Baltimore, Maryland from 1829 to 1837, in 1839, from 1841 to 1844, and from 1847 to 1853.

[2] Giles was elected as a Democrat from Maryland's 4th congressional district to the United States House of Representatives of the 29th United States Congress, serving from March 4, 1845, to March 3, 1847.

[2] Giles received a recess appointment from President Franklin Pierce on July 18, 1853, to a seat on the United States District Court for the District of Maryland vacated by Judge John Glenn.

[1] He was confirmed by the United States Senate on January 11, 1854, and received his commission the same day.

[2] Giles issued the original writ of habeas corpus in Ex parte Merryman.