Until 1986, he worked as Robert Conquest's assistant on the book The Harvest of Sorrow on the Great Famine in Ukraine.

The conclusions of the report, in particular, stated that Joseph Stalin and his people committed genocide against Ukrainians in 1932–1933.

He is survived by his wife, Natalia Dziubenko-Mace, one son from a previous marriage, William, and two adult stepchildren.

[1] The Order of Yaroslav Mudry, 2nd Class was awarded posthumously to Mace by President Viktor Yushchenko, in 2005.

[9] Streets in the Ukrainian cities of Kyiv, Brovary, Dnipro and Vinnytsia have been renamed after James Mace.