Plea

At the trial the appellant pleaded guilty. The simple question is what is the effect of a plea of guilty to a criminal charge?
When an accused person represented by counsel is arraigned and the charge read and explained to him in the language he understands, and he pleads guilty, the Court shall convict him unless there appears to the Court sufficient cause why he should not be convicted.
A plea is valid only when the accused pleads himself. A trial would be declared a nullity if a plea is made by counsel. It is the duty of defence counsel to guide the accused person on how to plead and the consequences of pleading one way or the other. Once the trial Court is satisfied with the Plea of guilty, the next step is conviction and sentence.

The sine qua non for the plea, under Section 36(9) of the Constitution, is the conviction or acquittal by a Court of competent jurisdiction. See CHIEF OF AIR STAFF v. IYEN (2005) 6 NWLR (pt.922) 496. A plea of autrefois convict founded on the fact of a plea bargain arrangement presupposes that the fact of the plea bargain arrangement was before a Court of competent jurisdiction, and that Court, upon the plea bargain arrangement, convicted the accused person for some offence(s).

PML (NIGERIA)

In other words, while acknowledging the application of the doctrine in other jurisdictions such as United States of America and England, this Court made it clear in that case – Nafiu Rabiu V. State (supra) that it is primarily the Constitution of the Federal Republic of Nigeria that determines the application of the said Doctrine in this Country
By Section 36 (9) of the 1999 Constitution, an accused person, who shows that he had been tried for a criminal offence, and was convicted or acquitted, shall not be tried again for the same offence or for a criminal offence having the same ingredients as that offence.
For the plea of autrefoit acquit or autrefoit convict to succeed, the following factors must be proved to the Courts satisfaction
1. That the Accused had previously been tried on a criminal charge.
2. The former trial must have been conducted before a Court of competent jurisdiction.
3. The trial must have ended with an acquittal or a conviction
4. The criminal charge for which the Accused was tried should be the same as the new charge against him or alternatively the new charge should be one in respect of which the Accused could have been convicted at the former trial, although not charged with it. See Sunday V. The State (2017) LPELR-42140(CA) per Oho, JCA

PML (NIGERIA)