Title II
Rights
CHAPTER EIGHT
Rights to protection
Article 76. In all processes where rights and obligations of any kind are set forth, the right to due process of law shall be ensured, including the following basic guarantees :
7. The right of persons to defense shall include the following guarantees :
j) Those who act as witnesses or experts shall be required to appear before the judge or authority and to answer the respective questions.
Procedure for witness testimony - national proceedings
EDIT.