The Legal Effect of Previous Convictions and Acquittals in Tanzania.

The Legal Effect of Previous Convictions and Acquittals in Tanzania.

In criminal law, the principle that a person should not be tried twice for the same offence is fundamental to justice and fairness. This doctrine, commonly referred to as double jeopardy, is clearly enshrined in the Tanzanian legal system under the Criminal Procedure Act [Cap. 20 R.E. 2022], particularly in sections 137 to 141. These provisions safeguard against abuse of process while also clarifying circumstances under which further prosecution may still be lawful.

No Double Trial for the Same Offence.

Section 137 provides that a person who has already been tried and either convicted or acquitted by a court of competent jurisdiction cannot be tried again for the same offence based on the same facts—unless that previous conviction or acquittal has been lawfully set aside. This provision reinforces the finality of judicial decisions and protects individuals from facing repetitive legal harassment for offences they have already answered for.

Trial for Other Offences Arising from the Same Facts.

However, the law does allow exceptions. Under section 138, a person who was convicted or acquitted of an offence may still be tried later for a different offence that could have been included in the same charge under section 134(1). This means that if someone could have been charged with multiple offences based on the same incident, but only one was initially pursued, the remaining charges may still be brought, subject to legal safeguards.

New Consequences Unknown During the First Trial.

Section 139 covers scenarios where new consequences of an act arise after the initial trial or were unknown at that time. If a person was tried for an act but later consequences emerge which turn the same act into a different or more serious offence, they may be tried again. For example, if someone was convicted for assault but the victim later dies from injuries previously undetected, the accused may be tried for manslaughter or murder.

Jurisdictional Limitations of the Original Court.

Section 140 introduces another exception: if the first court lacked the jurisdiction to try a more serious offence arising from the same act, the accused can later be charged and tried before a competent court. This ensures that jurisdictional limitations of the first trial do not bar justice from being served in full.

Proof of Previous Conviction.

The question of how a prior conviction is proved is addressed in section 141. A previous conviction may be established through various official documents, including:

• A certified extract from the court records;

• A certificate from a prison officer where punishment was served;

• The warrant of commitment; or

• A final judgment of a competent court.

Importantly, these must be accompanied by reliable evidence identifying the accused as the same person previously convicted.

Additionally, subsection (2) introduces the use of fingerprint evidence. A certificate from an officer appointed by the Director of Public Prosecutions, confirming that the accused’s fingerprints match those of the previously convicted person, is considered prima facie evidence—provided it is presented by the officer who collected the fingerprints.

Subsections (3) and (4) expand this framework to include foreign convictions. A conviction from outside Tanzania can be proved using certificates from police officers of that country, including fingerprint or photograph comparisons. These certificates, if appearing genuine and presented according to the procedure, are taken as valid without requiring further proof of the authority or signature of the officer who issued them.