RTÉ.ie presented a live webcast of the 2007 Amnesty International Lecture by Seymour Hersh at Trinity College in Dublin on 24 October. Watch It Now
The award-winning investigative reporter has exposed a number of US government secrets dating back to the Vietnam War.
Outside of the US, Mr Hersh is perhaps best known for his 2004 story on Abu Ghraib, which revealed the abuse of Iraqi prisoners at the hands of US soldiers.
However Abu Ghraib is just one of many investigations Mr Hersh has conducted into US foreign policy, security and the military.
Originally from Chicago, Mr Hersh graduated from college with the intention of pursuing law.
However he left law school and strayed into journalism, starting his career working for Chicago's legendary City News Service.
He eventually moved to Washington DC, and in the late 1960s was appointed as Pentagon Correspondent for the Associated Press.
Mr Hersh was working independently at the time and the story was carried in several news magazines.
After the My Lai story Mr Hersh was hired by the New York Times to work out of its Washington DC bureau where he broke several stories on the actions of the US Central Intelligence Agency as well as the Watergate scandal.
In the early 1980s he wrote his fourth book The Price of Power: Kissinger in the Nixon White House.
Mr Hersh wrote about Henry Kissinger's secret bombing of Cambodia in this book, which was one of his most controversial publications.
Most of Mr Hersh's writings have been veiled in controversy and with almost four decades of reporting in Washington D.C. sources are often reluctant to talk to him.
But the 70-year-old is still filing stories and writing books.
At present he writes for the New Yorker magazine.
Read more about Seymour Hersh's Top 5 Stories
Plus, watch Paul Cunningham's interview with Seymour Hersh on One to One.
