Gallagher studied at University College Dublin and graduated in 1999 with a Bachelor's degree in Civil Law.[4] She also holds degrees from the Honorable Society of the King's Inns, Dublin; and Cambridge University.[5]
She is one of the three joint founders of the ‘Act for the Act’ campaign (with Martha Spurrier and Fiona Bawdon), a crowdfunded advertising campaign to tell positive stories about the Human Rights Act 1998.[6]
At the 2017 Freedom of Expression Awards (2nd from right)
Gallagher has spoken about the importance and value of pro bono work. She has represented survivors of the Hillsborough disaster and the 7/7 bombings.[10]
In 2022, she spoke out against what she saw as anti-Irish[1] and anti-lawyer talk made by British government ministers. She thought these were a result of Brexit. She had personally received death threats and Amnesty International supported her view that politicians should be more cautious in their accusations against lawyers and judges.[12]
In 2023, she was appointed to the Irish independent role of Special Rapporteur-for Children. She replaced Professor Conor O'Mahony and will serve for three years.[4]