How to justify failure to follow chain of custody?

Thus, in People v. Almorfe[5], the Supreme Court stressed that:
Respecting the team’s non-compliance with the inventory, not to mention the photograph, requirement of R.A. No. 9165, the same does not necessarily render void and invalid the seizure of the dangerous drugs. There must, however, be justifiable grounds to warrant exception therefrom, and provided that the integrity and evidentiary value of the seized items are properly preserved by the apprehending officer/s.For the saving clause to apply, it is important that the prosecution should explain the reasons behind the procedural lapses and that the integrity and value of the seized evidence had been preserved. [N]on-compliance with the strict directive of Section 21 of R.A. No. 9165 is not necessarily fatal to the prosecution’s case; police procedures in the handling of confiscated evidence may still have lapses, as in the present case. These lapses, however, must be recognized and explained in terms of their justifiable grounds and the integrity and evidentiary value of the evidence seized must be shown to have been preserved.[6]
[1] People v. Bara, G.R. No. 184808, November 14, 2011.
[2] Zafra v. People, G.R. No. 190749, April 25, 2012.
[3] G.R. No. 182417, April 3, 2013.
[4] People v. Ancheta, G.R. No. 197371, June 13, 2012.
[5] G.R. No. 181831, March 29, 2010.
[6] G.R. No. 181831, March 29, 2010, at 59-60.