P.R. Laws Ap. tit. 34A, § II, Rule 137
After the arguments, the court shall charge the jury, summing up the evidence and stating all the questions of law necessary for their information. By stipulation of the parties filed immediately before beginning the instructions and approved by the court, the summary of the evidence may be omitted. All the instructions shall be oral unless the parties consent to the contrary. Either party may present to the court any written request that certain instructions be given, at the end of the evidence, or prior thereto if the court reasonably so orders. A copy of said request must be served on the adverse party. The court may accept or refuse any or all the requests, indorsing its decision on each one, and shall give its decision to the parties before they argue to the jury. Neither party may assign as error any portion of the instructions or omission therein unless objection is raised thereto or additional instructions are requested before the jury retires to deliberate, stating clearly the grounds of challenge or of its request. An opportunity to make such objection or request outside the presence of the jury shall be given to both parties. The court shall then proceed to decide the matter, entering its decision in the record or giving any additional instruction which it might deem pertinent. After giving its instructions the court shall appoint a foreman of the jury and shall order that the jury retire to deliberate. In their deliberations and verdict the jury are bound to accept and apply the law as stated by the court in its instructions.