DENVER -- When the city of Denver said Kevin O'Connell's dog was a pit bull, they took away his best friend.

Now, one dog owner's win in court is putting Denver's controversial pit bull ban back in the spotlight.

"He never gets tired," said O'Connell, as he threw a tennis ball for his 4-year-old boxer-mix, Dexter. "He's always by my side. He sits in the front seat of my car whenever we go anywhere."

During one business trip in July, though, O'Connell left Dexter with a friend in Denver.

An animal control officer responding to an unrelated call saw Dexter in the back yard, thought he was a pit bull and took him to the pound.

He went through an examination process and the city found him to have a majority of pit bull characteristics.

Because O'Connell lives in Thornton, he was able to take Dexter out of city limits, but he set about the task of proving the animal control officers wrong.

"I just picked him up and got him out of there and went to work," he said.

He had American Kennel Club and United Kennel Club judges evaluate his pet, and they found the dog was not a pit bull and did not display a majority of pit bull characteristics.

He also hired a trial attorney for the hearing.

Jennifer Edwards, founder of the Animal Law Center, said the process behind Denver's pit bull ban is too vague.

"Two animal control officers and a vet tech have no business evaluating breeds of dogs," said Edwards.

In the end, they won.

An administrative judge ruled Dexter isn't a pit bull under Denver's definition.

"This verdict shows that Denver cannot enforce its pit bull ban," said Edwards. "They do not have qualified experts in order to enforce the ban and determine the breeds of the dogs."

O'Connell said he is just glad he could fight the system and still have Dexter by his side.

He has to pay attorney fees, impound fees and vet fees, though.

If he hadn't won and his dog had been labeled a pit bull, he said Dexter could have been put down if he was ever caught again in Denver or any city with a pit bull ban.

"I hope that nobody else has to go through this," he said.

Pit bull supporters say the win is a step towards fighting the ban.

Edwards said she hopes it will encourage more people to fight when the city’s animal control evaluators decide a dog is a pit bull.