If you want to contest your parking tickets, there are certain defenses you can offer. 

District of Columbia law (Official Code Section 50-2303.5 (a) (2)) provides seven defenses for parking violations: 

1. You were not the owner or lessee of the cited vehicle at the time of the infraction.
2. The cited vehicle or its state registration plates were stolen at the time of the violation (requires full police report).
3. The relevant signs prohibiting or restricting parking were missing or obscured.
4. The relevant parking meter was inoperable or malfunctioned through no fault of the person who received the ticket.
5. The facts alleged on the parking violation notice are inconsistent or do not support a finding that the specified regulation was violated.
6. The vehicle was suddenly mechanically disabled, provided that the vehicle was removed as soon as practicable.
7. The operator suddenly needed immediate medical assistance (proof of medical attention is required). 

Your parking ticket can be dismissed only if one of these seven defenses is successfully raised. You should provide evidence to support your defense when you contest online or by mail request to: 

DMV Adjudication Services
ATTN: Mail Adjudication
PO Box 37135
Washington, DC 20013

Note: If you are issued a ticket while driving a rental car, rental car agreements provide that a rental party is responsible for all tickets issued to the rental vehicle during the rental period. DC DMV has discovered that some rental car companies will automatically pay any ticket(s) incurred on vehicles and charge the customer the ticket fine plus administrative fees. They will not provide you with the opportunity to adjudicate the tickets, as the adjudication process ends once a ticket is paid even if the ticket is going through the adjudication process. As the legal owner of the vehicle, rental car companies are within their rights to use this process. 

Most parking tickets in the District are written by the DC Department of Public Works (DC DPW). If you receive a parking ticket issued by DC DPW, you may visit the DC DPW website, then search TICPIX to see images of the parking violation and resulting ticket. Any images available will be posted 72 hours after a ticket is issued, but not all violations will have associated pictures.