The witness is the important part of a court trial. Their statements made before the courts are treated as the evidence for that case. They are included in the category of oral evidence. Generally, the witness is a person who sees an event and can tell about that event. Chapter IX of the Evidence Act, 1872 has 16 sections from 118 to 134 which tell about the competency of any people as a witness, privileges, and general rules. Generally, any person can be compelled to be a witness in the case except President and Governor during their office.
COMPETENCY OF WITNESS
But here the evidence acts, specify the competency of the witness. Section 118 mentions that all people are competent unless the court considers that the particular person is not able to understand the question or not able to give a rational answer, due to the tender years, very old age or diseases of body or mind, or any other reason. It is specifically mentioned in this section that lunatic people can testify if he/she is able to understand the question and give rational answers. There is a judgment of the Supreme Court [I] in which the court clarifies that a young child can be allowed to corroborate the evidence if he is able to answer the question rationally. But the child testimony should be dealt with cautiously as a child is easy to be swayed [II].
A witness can be disallowed if he/she is not able to communicate verbally. His statements can be recorded in written or in sign language and if the court is not able to understand the sign language, the court can appoint the expert to translate and that should be video graphed. [III] These pieces of evidence will be oral evidence.
The husband or wife of any party in a civil proceeding or in a criminal proceeding is competent evidence [IV]. But people in relation to marriage cannot be compelled to disclose communication made between nor can the permission be granted to disclose unless that person allows it or the civil or criminal suit against each other. [V]
Accomplice, who is the co-accused, is a competent witness and the judgment made only on the basis of the testimony of the accomplice cannot be illegal [VI]. The accomplice is considered of three types: 1. The main instigator of the crime or any offense; 2. The person who played an active role in the crime; 3. The person who helped after the conduct of the crime. But section 133 should be read along with illustration (b) of section 114 which mentions that it is always unsafe to convict upon the testimony of the accomplice [VII].
Section 121 mentions the privilege of judge or magistrate where he cannot be compelled to answer any question about his conduct as a judge or magistrate and anything which came to his knowledge as a judge or magistrate. But he can be compelled to answer on the order of the higher court. Section 122 mentions the privilege of the communication made between husband and wife. It is already explained in the above section. Section 123 to section 125 mentions the privileges of the state and its official. Section 123 mentions that no one can give evidence derived from the unpublished official records which can be derived after the permission of the officer at the head of that department who has the discretion with himself. The document should be published, published illegally or improperly is immaterial. The documents derived improperly and then the attempt is made by production thereof to compel the state to produce the original, then it is at the discretion of the court under section 162 of the Evidence Act to order the officer.
Section 124 mentions the official communication privilege which is done between the public officers. No public officer can be compelled to disclose the communication if he thinks that public interest may suffer.
Section 125 mentions privilege which is given to the informer. No police officer or magistrate can be compelled to disclose about the source from they got information about the commission of any offense or revenue officer cannot be compelled to answer about the source of information from where he gets to know about the offense committed against public revenue.
Section 126-129 deals with the privileges between the lawyer, barrister, or vakil and his client. Section 126 mentions that no barrister, attorney, or vakil cannot be permitted to disclose the communications between him and his clients as a barrister, attorney, or vakil. There is no exception to this privilege that if that communication is made in furtherance of the illegal purpose and if the barrister, attorney, or vakil observe any fraud or crime committed since the beginning of his employment. It is clearly mentioned in the explanation that this privilege will remain in force after employment also.
Section 127 extends the application of section 126 to the clerks of the barrister, attorney, or vakil and the interpreters. If any party to the suit itself gives any evidence, then it does not give consent to the disclosure under section 126 [VIII].
Section 130 gives immunity to the person who is not the party of the suit from producing any documents which tell about his title to any property or any holding as pledge or mortgagee or any document which tend to criminate him unless he gives that in writing.
Section 131 gives immunity to deny the production of any document or any electoral record which in his possession and any other person who would have been in the possession and deny the production unless the last-mentioned person consents for the production.
Section 132 compels the person to answer the question who is not giving witness on the basis that such witness will criminate him. But this section also gives immunity to that person that he cannot be arrested or prosecuted or to be proved against him in any criminal proceeding. If he gives the wrong answer to such a question then the prosecution can be initiated against him. Policy under Section 132 of the Evidence Act, 1872 appears to be to secure evidence from whatever sources it is available for doing justice in a case brought before the court [IX].
NUMBER OF WITNESSES
Section 134 makes clear that no particular number of witnesses is required for proof of any fact. A conviction can be based on the testimony of a single witness if he is wholly reliable. Corroboration may be necessary when he is only partially reliable. If the evidence is unblemished and beyond all possible criticism and the court is satisfied that the witness was speaking the truth then on his evidence alone conviction can be maintained [X].
 Bharvad Bhika Valu v State of Gujarat, 1971 SCC(Cri) 500
[II] Digamber Vaishnav v State of Chattisgarh (2019)
[III] Evidence Act, 1872 Section 119.
[IV] Evidence Act, 1872 Section 120
[V] Evidence Act, 1872 Section 122
[VI] Evidence Act, 1872 Section 133
[VII] Mohammad Hussain v K.S. Dalipsinghji, (1969) 3 SCC 429