[1] Born in The Burren, County Clare, Ireland, O'Donohue graduated as a civil engineer from University College, Galway in 1954.
In April 1989, O'Donohue introduced a by-law at City Council to ban the manufacture, sale, distribution and use of ozone depleting substances.
As a result, he was invited to make a presentation on the Toronto by-law at the Beckman Institute of the National Academies of Science and Engineering, in Irvine, California.
While there, he consulted world-renowned chemist and later Nobel laureate Frank Sherwood Rowland on how to help prevent the dumping of ozone depleting substances into the atmosphere.
[4] He argued that the city paid millions of dollars to make sufficient beds available for the homeless and there was no need for anyone to lie or sleep on the sidewalks.
O'Donohue made news in 2002 as a result of his legal challenge to the Act of Settlement barring Roman Catholics from the throne of Canada.
[9][10] In the present case the court is being asked to apply the Charter not to rule on the validity of acts or decisions of the Crown, one of the branches of our government, but rather to disrupt the core of how the monarchy functions... To do this would make the constitutional principle of Union under the British Crown together with other Commonwealth countries unworkable, would defeat a manifest intention expressed in the preamble of our Constitution, and would have the courts overstep their role in our democratic structure...
"Following the Changing Atmosphere Conference in July, 1988, O’Donohue embarked a plan to make Toronto a leading world city in urban environmental issues.