He was a lawyer of the Bar Associations of Madrid, A Coruña, Vigo and Lugo, president of the Agrarian Chamber of Lugo, Member of Parliament in 1977 and during the sessions 1979-82 and member of the mixed commission that reported the Statute of Galicia. He was on the commissions of Justice, Agriculture and Industry in the Parliament. He was a rapporteur of the Law regulating the commonable lands, family farms and mountain agriculture. He was the president of the Commission of Industry that reported on the Law regulating the Electric Energy Production and participated in the National Energetic Plan. He was the founder and first president of ‘Coalición Galega’.
The Ministry of Justice, on a proposal from the Bar Association of Lugo, awarded him the Cross of the Order of St Raymond of Penyafort in 2013.
In addition to many journalistic articles about politics, justice and agriculture, Antonio Díaz Fuentes is the author of Dereito Civil de Galicia. Comentarios á Lei 4/1995, publication of the Seminary of Galician Studies, Do Castro Publications, 1997, Montes vecinales en mano común, Bosch, Barcelona, 1999, Toponimia de la Comarca de Sarria, Publication Service of the County Council of Lugo, 1998, División de herencias y liquidación del régimen económico matrimonial. Comentario a la Ley de Enjuiciamiento Civil 1/2000, Bosch, Barcelona, 2001, La prueba en la nueva Ley de Enjuiciamiento Civil, Bosch, Barcelona, 2002 and Cuentos de pueblo. Cuentos de Sarria, 2003. Besides, he collaborated in the reprint of Práctica Procesal Civil by Brocá y Majada.