Polkadot Slashing: A Penalty System for Misbehaving Validators

Polkadot's slashing mechanism is a penalty system that removes part of the staked DOT when a validator breaks network rules. Validators are nodes that produce and check blocks, while nominators are token holders who back validators with their own DOT. The staked DOT works like a security deposit, and if a validator misbehaves, the protocol takes a share of it.

The official Polkadot documentation says Polkadot slashing can range from 0.01% to 100% of the stake, depending on severity. Nominators backing the offending validator can lose funds too, at least under the current rules. Penalties make dishonest behavior expensive in a public, permissionless network where anyone can run a node.

Invalid votes and equivocations trigger Polkadot slashing. Invalid votes happen during block inclusion and approval, while equivocation means a validator signs conflicting statements. Most honest cases share one cause: duplicate signing keys. If the same keys sit on two machines, both can sign at once.

The official docs use four threat levels to determine penalties. Offenses that need coordination or heavy computing costs get tougher penalties than likely mistakes. The slashing mechanisms research page explains the reasoning behind each tier.