The current impeachment trial has imparted many lessons to Filipinos, here are a few of them:

Proffer of evidence vs. Offer of evidence
 

A proffer of evidence is proper whenever a court disallows or refuses to permit counsel to present testimony which he thinks is competent, material and necessary to prove his case. It is the proper method of preserving the record to the end that the question may be saved for the purpose of review.

An offer of evidence is done so that the court may consider the evidence presented by counsel. Under the Rules of Court, the court shall consider no evidence which has not been formally offered. The purpose for which the evidence is offered must be specified.

Material evidence vs. Relevant evidence
 

According to eminent jurists there is no distinction between materiality and relevancy.  Both terms have been used interchangeably in numerous cases.  Evidence is relevant when it has a tendency in reason to establish the probability or improbability of a fact in issue.

Adverse witness vs. Hostile witness
 

A hostile witness is one who manifests so much hostility or prejudice under examination-in-chief that the party who has called him, or his representative, is allowed to cross-examine him, that is to treat him as though he had been called by the opposite party.

An adverse witness is one who must be adverse to the party calling him, and be actively seeking a recovery against, or opposing a recovery by, such party, or a person for whose immediate benefit the action was brought or defended.

Objection vs. Continuing objection
 

Every objection to the admissibility of evidence shall be made at the time such evidence is offered, or as soon thereafter as the objection to its admissibility shall have become apparent;otherwise, the objection shall be treated as waived. The grounds for the objection must be specified. 

Under the Rules of Evidence, when it becomes reasonably apparent in the course of the examination of a witness that the questions being propounded are of the same class as those to which objection has been made, whether such objection was sustained or overruled, it shall not be necessary to repeat the objection, it being sufficient for the adverse party to record his continuing objection to such class of questions.

Leading Questions and Misleading Questions
 

A question which suggests to the witness the answer which the examining party desires, is a leading question.

A misleading question is a question which assumes the truth of facts which are in issue or assumes material facts which have not been proved, or certain answers to have been given to prior questions, when such answers have not been given. It is not allowed.

Subpoena duces tecum vs. Subpoena ad testificandum
 

A subpoena ad testificandum is a process directed to a person requiring him to attend and to testify at the hearing or trial of an action or at any investigation conducted under Philippine laws or for the taking of his deposition.

A subpoena duces tecum is a process directed to a person requiring him to bring with him any books, documents, or other things under his control.