Spoliation is the destruction, alteration or loss of evidence that a party had a duty to preserve. The duty attaches when litigation is reasonably anticipated, which is usually earlier than a party assumes.

Sanctions scale with culpability and prejudice. Negligent loss may draw additional discovery, cost-shifting, or measures to cure the prejudice. Loss with intent to deprive the other side of the evidence opens the severest remedies: an instruction that the jury may presume the lost material was unfavourable, exclusion of related evidence, or dismissal or default.

Two features make spoliation disproportionately damaging. It is a claim about the party’s conduct rather than the dispute, and it is raised at every subsequent stage. And it usually happens by accident — automated deletion policies running as designed on custodians nobody thought to include in a hold.

The defense is procedural and boring: a documented preservation notice, suspension of automated deletion, and a record of what was preserved and when.