McCarthy is a graduate of Cardinal Hayes High School in the Bronx in New York City. He was also educated at Columbia College and New York Law School, and has served as a professor at the latter and at Fordham University Law School.
He is currently a senior fellow at the Foundation for Defense of Democracies, serving as the director of the FDD's Center for Law and Counterterrorism. He has served as an attorney for Rudy Giuliani, and is also a conservative opinion columnist who writes for National Review and Commentary.
He has defended the practice of waterboarding as not necessarily being torture, and as necessary in some situations to prosecute the War on Terror whilst admitting that "waterboarding is close enough to torture that reasonable minds can differ on whether it is torture".
During the 2008 presidential election campaign, McCarthy wrote a number of posts on the National Review's Corner blog stating that he thought that Democratic Presidential candidate, Barack Obama, was not serious about protecting US national security against threats from radical Islam and elsewhere, and that Obama had a number of troubling ties and associations with leftist radicals.
In an opinion posted on the blog 'the Corner' on October 22, 2008, McCarthy wrote "I believe that the issue of Obama's personal radicalism, including his collaboration with radical, America-hating Leftists, should have been disqualifying."
In May 2009, McCarthy provided details of a letter declining an invitation from Attorney General Eric Holder for a round-table meeting with President Barack Obama concerning the status of people detained in the War on Terror. McCarthy noted his dissension with the administration in their policies regarding the detainees. On December 5, 2009 he came out publicly against prosecuting Islamic terrorists in civil courts rather than military tribunals, saying "A war is a war. A war is not a crime, and you don’t bring your enemies to a courthouse."
McCarthy has recently spoken out against the War in Afghanistan, saying that the War benefits the Afghans while hurting American interests, and that the United States should be concerned solely with its interests.
Coupled with his national security conservatism, McCarthy also espouses strong fiscal conservative views on entitlement spending, and favors the abolition of Medicare, which he calls a fraud and a Ponzi scheme greater than that perpetrated by Bernie Madoff. He says that the goals of the original proponents of Medicare were to get a foot in the door with "a Trojan Horse, whose proponents wanted universal compulsory socialized medicine."
McCarthy opposed the 2017 Shayrat missile strike.Willful Blindness: Memoir of the Jihad (2008)
How Obama Embraces Islam's Sharia Agenda (Encounter Broadsides, 2010) ISBN 978-1-59-403558-6
The Grand Jihad: How Islam and the Left Sabotage America (2010)
How the Obama Administration has Politicized Justice (Encounter Broadsides, 2010)
Spring Fever: The Illusion of Islamic Democracy (Encounter Books, 2013) ISBN 978-1-59-403691-0
Faithless Execution: Building the Political Case for Obama's Impeachment (Encounter Books, 2014)
Islam and Free Speech (Encounter Broadside, 2015) ISBN 978-1-59-403748-1