Private individuals may bring lawsuits asking for court orders to stop discrimination. Individuals may also file complaints with the United States Attorney General, who is authorized to bring lawsuits in cases of general public importance or where a "pattern or practice" of discrimination is alleged. In these cases, the Attorney General may seek monetary damages and civil penalties. Civil penalties may not exceed $55,000 for a first violation or $110,000 for any subsequent violation.
For additional information, take a look at the following resources:
FAQ: How can I file an ADA complaint with the U.S. Department of Justice?