Short answer. Because the volume seized was too large to finish testing in the required time. Section 21 lets the forensic laboratory provisionally issue a partial report stating the quantities still to be examined, with a final certification to follow once testing is complete. The partial report is a stopgap, not the end result.
What the law says
a partial laboratory examination report shall be provisionally issued stating therein the quantities of dangerous drugs still to be examined by the forensic laboratory
RA 9165, Section 21 — Chain Of Custody. Read the full provision →
The rule the partial report comes from
Section 21 tells the forensic laboratory to certify results immediately upon receiving the seized items. It then adds a carve-out for bulk seizures: where the volume does not allow testing to be completed within the time frame, a partial laboratory examination report shall be provisionally issued stating therein the quantities of dangerous drugs still to be examined by the forensic laboratory. So a partial report is not a sign that something went wrong. It is the mechanism the statute itself provides for cases where there is simply too much material to test at once within the deadline the law sets.
What a partial report has to state
The statute does not let the laboratory issue a vague interim note. The partial report must state the quantities still to be examined. That requirement keeps the whole seizure accounted for on paper: the portion already tested and confirmed, and the portion that remains outstanding, are both written down. It is what allows anyone reading the file to see that the untested balance has not quietly disappeared, and to match the eventual final result against the amount the partial report said was still to come.
A final certification must still follow
A partial report is provisional by design. Section 21 requires that a final certification shall be issued immediately upon completion of the said examination and certification. In other words the laboratory owes the case a complete result in the end; the partial report only buys time for a large volume. When reviewing a file that contains only a partial report, the natural question is whether the final certification was ever issued, and whether the quantities in it reconcile with what the partial report flagged as still to be examined.
Why the distinction can matter to a case
The amount of a dangerous drug can bear on the charge and its consequences, so which quantity has actually been confirmed by testing — as opposed to merely seized and awaiting examination — is not a trivial detail. A partial report and the final certification are different documents doing different jobs, and both belong in the record. Anyone concerned about how a seizure was quantified should gather the inventory, the request for laboratory examination, the partial report and the final certification together, and have them reviewed as a set rather than one at a time.