What triggers a boot?
Each city sets its own threshold — but the most common is 3+ unpaid parking citations (or 2+ citations older than 1 year). Once booted, you must pay the unpaid citations PLUS a release fee (typically $150-$300) within 24 hours, or the vehicle is towed.
Towing on private land
Private-land towing must comply with state law (e.g. Cal Veh Code §22658 in California, FL Stat §715.07 in Florida, TX Occupations Code §2308 in Texas). The signage, notification, and tow-storage rules are strict — non-compliance makes the tow unlawful and the fee recoverable.
How to fight an unlawful tow
Photograph the location and signage immediately. Demand the tow company's invoice and the tow authorization. If signage was missing, non-compliant, or you were not parked on the towing operator's lot, file a complaint with the state regulator (or sue in small-claims court) for refund of the tow and storage fees.