He started practicing his profession in 1941 and in 1946 became a partner in the Tañada, Pelaez and Teehankee law office. Around this time, he joined Senators Lorenzo Tañada and Claro M. Recto in organizing the Citizen's Party. 


On January 15, 1966, President Ferdinand E. Marcos appointed Teehankee as undersecretary of justice. A year later, on August 5, 1967, he was designated justice secretary. 



In November 1968, Teehankee was elevated to the Supreme Court as one of its associate justices. He distinguished himself when he upheld the rights of the people even during the height of the martial law period. Teehankee often dissented from the majority opinion of his colleagues in the court, accusing Marcos and the military of human right abuses. He authored the opinion questioning the jurisdiction of military commissions over civilians, such as the one that tried former Senator Benigno S. Aquino Jr. In his role as "great dissenter", Teehankee was called the "conscience of the Supreme Court". When he became a senior member of the Senior Court, Teehankee was twice bypassed for the position of Chief Justice, violating the protocol that the most senior of the justices be named to head it. 


Teehankee weathered the bar scandal of 1982, which involved the son of another Supreme Court justice, and was reappointed to the court. He also survived attempts to impeach him and questions concerning his citizenship during the same year.


At the height of the EDSA Revolution in February 1986, Teehankee played a crucial role in swearing in Corazon C. Aquino as the country's 11th President while Marcos was holding his own inaugural ceremony at Malacañang. 


Teehankee was appointed as Chief Justice by the Aquino administration in 1986 and served until his retirement on April 18, 1988. He died of cancer in New York on November 27, 1989 at the age of 72. 


<h4>
Source:
</h4>

<ol class="article-sources">
<li>
Fernan, Marcelo B. “A Tribute to Dingdong Teehankee” Manila Bulletin (December 17, 
1989)
</li>
<li> 
Retizos, Isidro L. & Soriano, D.H. Philippines Who’s Who. Quezon City: Capitol Publishing 
 House, Inc., 1981. 
</li>
<li> 
Sevilla, Victor J. Justices of the Supreme Court of the Philippines Volume III Quezon City: the 
 Author & New Day Publishers, 1985 
</li>
</ol>

April 18, 1918: Claudio Teehankee was born in Manila