Section 1. Article 81 of the Revised Penal Code, as amended by Section 24 of Republic Act No. 7659 is hereby further amended to read as follows:

"Art. 81. When and how the death penalty is to be executed. — The death sentence shall be executed with preference to any other penalty and shall consist in putting the person under the sentence to death by lethal injection. The death sentence shall be executed under the authority of the Director of the Bureau of Corrections, endeavoring so far as possible to mitigate the sufferings of the person under the sentence during the lethal injection as well as during the proceedings prior to the execution.

"The Director of the Bureau of Corrections shall take steps to ensure that the lethal injection to be administered is sufficient to cause the instantaneous death of the convict.

"Pursuant to this, all personnel involved in the administration of lethal injection shall be trained prior to the performance of such task.

"The authorized physician of the Bureau of Corrections, after thorough examination, shall officially make a pronouncement of the convict's death and shall certify thereto in the records of the Bureau of Corrections.

"The death sentence shall be carried out not earlier than one (1) year nor later than eighteen (18) months after the judgment has become final and executory without prejudice to the exercise by the President of his executive clemency powers at all times."