He has been a lawyer since 1982 and became a partner at Vasconcelos, F. Sa Carneiro, Fontes & Associados in 1994, where he headed up the Litigation Department and focused his practice on litigation, arbitration and labour law.

From 1983 to 1987, Tito was a legal adviser at the Caixa Geral de Depósitos (Personnel Department), legal adviser to the Secretary of State for Higher Education from 1987 to 1991, legal adviser to the Secretary of State for Local Government and Regional Planning from 1991 to 1992, a lawyer at the Caixa Geral de Depósitos (the Litigation Department) from 1991 to 1992, Secretary General of the Union of Traders’ Associations of the Lisbon district from 1992 to 1993, and a member of the Management Committee of the Law Firms Institute (Bar Association) from 2002 until 2004.

Tito is the head of the Litigation Department covering all the practice areas (both contentious and non-contentious). He represents clients in civil, criminal and commercial procedures, at all instances including the higher courts and the Constitutional Court. He also acts in arbitration hearings either as an arbitrator or as lawyer representing parties in insolvency procedures and in particular before the Commercial Court (Tribunal de Comércio). Tito represents Portuguese and foreign companies before the Portuguese courts and arbitration tribunals and also actively participates in the negotiation, drafting and enforcement of complex agreements, often after years of litigation.

Chambers Global, 2007 says «Department head Tito Arantes Fontes climbs to the first tier following widespread recommendations from peers: “He is a truly excellent lawyer; bright, resilient and detail-oriented.” Clients also eagerly sing his praises: “He is impressive in court, knowing exactly when to ask the questions, and is more than willing to work through the weekend for us.”