As Uber fights over its ability to operate in states and countries alike, the car service company faces another legal battle of a different nature. The National Federation of the Blind has filed a federal civil rights suit citing examples of discrimination throughout the United States against blind customers with service dogs.

According to the suit, Uber drivers have refused to provide their service to customers with service dogs, charged cancelation fees and in some cases, harassed the potential riders. In one situation, the suit said that a Sacramento driver put a customer’s dog in the trunk and refused to pull over. The suit said that 30 customers were denied rides that they reserved through the Uber app on their phones. The National Federation of the Blind said that the reported discrimination violated the Americans with Disabilities Act.

Watchdog group Equal Rights Center conducted a study in 2010 that found that taxi drivers discriminated against those with service dogs. The group conducted 30 tests, placing a blind person with a guide dog and a sighted person without a dog in a high-traffic area to hail a cab. Even though the blind individual was placed 100 feet closer to oncoming traffic, half of the taxis passed by and picked up the sighted person.

Uber works differently than a cab. Users register, pay and order rides through the company's app. Uber is currently operating in 45 countries around the world, and approximately 100 cities in the U.S.