| Type: | Cardinal |
| Honorific Prefix: | His Eminence |
| Jean Jérôme Hamer | |
| Honorific Suffix: | O.P. |
| Prefect Emeritus of the Congregation for Institutes of Consecrated Life and Societies of Apostolic Life | |
| Church: | Roman Catholic Church |
| Appointed: | 27 May 1985 |
| Term End: | 21 January 1992 |
| Predecessor: | Eduardo Francisco Pironio |
| Successor: | Eduardo Martínez Somalo |
| Other Post: | Cardinal-Priest of San Saba "pro hac vice" (1985–96) |
| Ordination: | 3 August 1941 |
| Consecration: | 29 June 1973 |
| Consecrated By: | Pope Paul VI |
| Cardinal: | 25 May 1985 |
| Created Cardinal By: | Pope John Paul II |
| Rank: | Cardinal-Deacon (1985–96) Cardinal-Priest (1996) |
| Birth Name: | Jean Jérôme Hamer |
| Birth Date: | 1 June 1916 |
| Birth Place: | Brussels, Belgium |
| Death Place: | Rome, Italy |
| Alma Mater: | University of Fribourg |
| Motto: | Fideliter et constanter |
| Cardinal Name: | Jean Jérôme Hamer |
| Dipstyle: | His Eminence |
| Offstyle: | Your Eminence |
| See: | Lorium (titular see) |
Jean Jérôme Hamer, O.P., S.T.D. (1 June 1916 – 2 December 1996) was a Belgian Cardinal who was Prefect of the Congregation for Institutes of Consecrated Life and Societies of Apostolic Life from 1985 until 1992.
He was born in Brussels and joined the Dominican Order in 1934 taking the name of Jérôme. He received his religious training at La Sarte, a Dominican Study house near Huy (Belgium), and Louvain University. He did his military service and, during the Second World War, spent 3 months of 1940 as a prisoner. He was ordained on 3 August 1941. He continued his studies at the University of Fribourg, Switzerland, where he earned his doctorate in theology. He was on the teaching staff of the Pontificium Athenaeum Internationale Angelicum for the academic year of 1952–53.[1] He had been a staff member at the University of Fribourg since 1944, where he then returned and taught until 1962.
He was appointed secretary of the party in 1958 Secretariat for Promoting Christian Unity on 12 April 1969. Then, on 14 June 1973, he was appointed titular archbishop of Lorium and secretary of the Congregation for the Doctrine of the Faith.
He was consecrated on 29 June 1973 by Pope Paul VI. In 1974, the Congregation published a "declaration on procured abortion", re-asserting the Church's opposition to the controversial procedure since the publication of Humanae Vitae. He later helped in writing the document Persona humana on the topic of sexual ethics.
He remained at this position until Pope John Paul II appointed him Pro-Prefect of the Congregation for Institutes of Consecrated Life and Societies of Apostolic Life in 1984. At that time the title of Prefect was reserved for someone who was already a Cardinal.
He became Prefect of the Congregation when he was made Cardinal-Deacon of San Saba in the consistory of 25 May 1985, two days after which the full title was formally granted him. He resigned as the head of the Congregation on 21 January 1992. He opted for the order of Cardinal Priests after ten years and his deaconry was elevated pro hac vice to title on 29 January 1996. He lost the right to participate in a conclave when he turned 80 in 1996. He died on 2 December 1996 in Rome.