Gallagher's wife, Ann Gillespie, and her sister, Eibhlin, both served almost 10 years of a 15-year sentence for conspiracy and explosive charges.

[5] Gillespie maintains her innocence, saying police used evidence from a discredited scientist, Frank Skuse, but does not wish to reopen the case.

[7] During his period in Europe, Gallagher was a member of a number of committees including Fisheries, Economics and Monetary and Industry and Energy.

He returned to domestic politics to successfully contest the 2002 general election, and was appointed Minister of State at the Department of the Environment and Local Government in June 2002.

Following a period in this role, Gallagher was appointed as Minister of State at the Department of Transport from 14 February 2006 where he served until 14 June 2007.

[10] In the 2016 general election, he ran alongside sitting TD Charlie McConalogue as the two Fianna Fáil candidates in the new five-seat Donegal constituency.

In September 2024, Gallagher was selected to contest the 2024 general election for the Donegal constituency, along with Charlie McConalogue.