Maker-checker: when two-person rule is worth the friction
Maker-checker adds friction — so apply it only where the blast radius is high: money, access, and irreversible changes.
Use maker-checker for
- Manual balance adjustments / credits
- User restriction changes (freeze/unfreeze)
- Override of limits, fees, or risk flags
- High-value withdrawals / exceptions
Design it properly
- Mandatory reason codes + notes
- Diff view: old → new before approval
- Time-bound approvals (expires)
- Immutable audit entries for both maker and checker