The prohibition on excessive fines applies to the states and constrains punitive economic sanctions, including civil forfeiture.

What counts as a fine. A payment to the government as punishment for an offense. Civil forfeiture is at least partly punitive and is therefore subject to the limit.

Gross disproportionality. A fine is unconstitutional if grossly disproportional to the gravity of the offense. Courts consider the nature and extent of the conduct, whether it related to other illegal activity, the other penalties that may be imposed, and the harm caused.

Value of the property relative to the maximum statutory fine is a frequent comparator, and forfeitures far exceeding the fine for the underlying offense are vulnerable.

Ability to pay has been treated as relevant by several courts, though it is not universally accepted.

Municipal relevance. Escalating civil fines for code violations, per-day penalties that accumulate for years, and forfeiture of vehicles in connection with minor offenses have each been challenged successfully.

Practical drafting. Cap accumulating daily penalties, provide for hardship reduction, and tie the sanction to the harm rather than to the length of non-compliance alone.