So damaging would be the contents of Bureau of Internal Revenue (BIR) box to impeachment trial respondent Vice President Sara Duterte’s case that it ought to be called an entire "armory".

This was part of House prosecution panel Lanao del Sur 1st district Rep. Zia Alonto Adiong's witty word play as he touted the BIR box as more than a "smoking gun" in their quest to convict Duterte.

“Baka ito yata ‘yung smoking gun. In fact, hindi lang yata ito smoking gun, mukhang armory na itong box na ito (Perhaps this is the smoking gun. In fact, it's more than a smoking gun, as this box could contain an entire armory [or evidence])," Adiong said.

The sealed BIR box contains income tax returns (ITRs) submitted by the agency to the House Committee on Justice in compliance with a subpoena covering the tax filings of the Vice President, her spouse, and their financial interests.

This was during the committee level-deliberations on the four impeachment complaints filed against Duterte this year. The House has since submitted the articles of impeachment to the Senate.

The BIR box was among the last pieces of evidence that the justice panel tried to examine, but it had never been opened.

During the recent pre-trial conference (PTC) that saw the marking of documentary evidence, Duterte’s defense team opposed the opening of the box.

“From the very start na ayaw nila. It only speaks to us one thing na parang takot sila mabuksan itong box na ito,” Alonto Adiong said during a press briefing via Zoom.

(From the very start [Duterte's lawyers] didn't want to open it. It only speaks to us one thing--that they appear to be afraid to open this box.)

According to the prosecution, the tax documents are central to the impeachment article alleging unexplained wealth because they could help determine whether Duterte’s declared assets, liabilities and lawful income are consistent with one another.

The records are also expected to be compared with the Vice President’s statements of assets, liabilities and net worth (SALNs) and other financial documents as prosecutors seek to establish the unexplained wealth allegation.

What's confusing according to Adiong is that the defense is also expected to rely on BIR documents as part of its own evidence.

“So nagtataka ako, ang prosecution kung ganoon, isa po iyon sa kanilang ipipresenta as a way of also presenting to the court ‘yung kanilang defense, e bakit itong pinanggalingan ng ITR na pinanggalingan din ng kanilang magiging ebidensya ay ayaw nilang pabuksan,” he said.

(So I, the prosecution wonders, if that is the case, since it is one of the things they will present as part of their defense, why do they refuse to open the ITR source that will also be the basis of their evidence.)

He argued that opening the sealed box would give the impeachment court the complete financial picture instead of only selected records.

“The ITR box na galing po sa BIR, that will give us the whole financial picture of what we are discussing here regarding the SALN and the unexplained wealth. Mukhang ang gusto nila half-baked lang, huwag na nating pag-usapan ng buo,” added Adiong.

(It seems they only want it half-baked, not to discuss it fully.)

Another prosecution spokesperson, lawyer Benjamin “Jay” Tolosa Jr. said the defense’s objection was "very unusual" because the marking of exhibits is merely a procedural step during pre-trial and does not determine whether evidence will ultimately be admitted.

“Very unusual ho ’yan na (It’s very unsual that) even just the marking of the sealed BIR box was vehemently objected to by the other party,” Tolosa said.

He says that parties are free to mark the evidence they intend to present during trial and that admissibility is decided only later by the impeachment court.

Tolosa noted that the marking of exhibits was intended to simplify the proceedings by allowing the parties and the impeachment court to quickly identify and refer to specific documents tied to each article of impeachment during the trial.