The Rev. Juan José Arrieta Ibarrechebea, L.C., was born on August 19, 1956, in Baracaldo, Vizcaya, Spain. He joined the Legion of Christ on September 10, 1973. He was ordained a priest on August 15, 1983. From 1979 to 1996, he was a formator of legionaries in Rome. From 1988 to 1996, he served as assistant to the general director for the female branch of consecrated life in Regnum Christi. Since 1996, he has been part of the governing council of the educational works of the Legion and Regnum Christi in Rome. During the period from 1996 to 1999, he was the coordinator for apostolate in Italy.

During the years 2000 to 2004, he was part of the administrative council of the Pastoral Center Sacerdos. In 2007, he was appointed pastor of the parish of Our Lady of Guadalupe and Saint Philip the Martyr in Rome. He is part of the general council of the Legion by appointment of the pontifical delegate since January 31, 2011, and is the responsible counselor for the area of religious life of the Legion. He was appointed vicar general of the Legion of Christ by the Holy See during the extraordinary General Chapter of 2014.