(Los Angeles) The glee club members twirl their wheelchairs to the tune of “Proud Mary” and in joyful solidarity with Artie, the fellow performer who must use his chair even when the music stops.

The scene in Wednesday’s episode of the hit Fox series “Glee,” which regularly celebrates diversity and the underdog, is yet another uplifting moment – except to those in the entertainment industry with disabilities and their advocates.

For them, the casting of a non-disabled actor to play the paraplegic high school student is another blown chance to hire a performer who truly fits the role.

“I think there’s a fear of litigation, that a person with disabilities might slow a production down, fear that viewers might be uncomfortable,” said Robert David Hall, longtime cast member of CBS’ “CSI: Crime Scene Investigation.”

All of that is nonsense, said Hall: “I’ve made my living as an actor for 30 years and I walk on two artificial legs.”

Hall, 61, chair of a multi-union committee for performers with disabilities, is part of a small band of such steadily working actors on TV that includes Daryl “Chill” Mitchell, star of Fox’s “Brothers”; teenager RJ Mitte of AMC’s “Breaking Bad”; and ABC’s “Private Practice” newcomer Michael Patrick Thornton.

Veteran actress Geri Jewell, who has cerebral palsy, appeared on HBO’s now-departed “Deadwood.”

Mitchell, 44, whose credits included “Veronica’s Closet” and the film “Galaxy Quest” before he was injured in a motorcycle accident and “Ed” after he began using a wheelchair, is also a producer on the Sunday sitcom that’s in need of higher ratings if it is to survive.

For Mitchell, “Brothers” represents more than just another show: He calls it “a movement” that deserves support from the wider disabled community as well as the industry.

“This is what my life is. This is what I want the world to see,” he said. “I want to hold the networks accountable. If I can come out and do what I’m doing, they can come to the table.”

It’s not just TV that falls short of what Mitchell and others seek, including auditioning those with disabilities for roles that echo their situation and for roles in which it is irrelevant. (Then it’s up to them to prove they deserve the job, Hall said.)

In the theater world, advocacy groups for the disabled recently objected to the casting of Abigail Breslin (”Little Miss Sunshine”) as young Helen Keller in a Broadway revival of “The Miracle Worker,” and a hearing actor’s selection for a deaf role in the off-Broadway “The Heart Is a Lonely Hunter.”

In films, Daniel Day-Lewis received an Academy Award for his portrayal of a man with severe cerebral palsy in “My Left Foot” and Tom Cruise was nominated for an Oscar for playing a paralyzed Vietnam veteran in “Born on the Fourth of July.”

Television, however, has a unique place in the country’s cultural and social fiber. It deals in volume, is entrenched in most lives as it consumes hours of leisure time and has the daily power to reinforce attitudes or reshape them. Increasingly, it’s been expected to reflect America in whole and not just the so-called mainstream.

That was the intent in assembling the cast of “Glee,” said executive producer Brad Falchuk, along with getting the best performers possible.

“We brought in anyone: white, black, Asian, in a wheelchair,” he said. “It was very hard to find people who could really sing, really act, and have that charisma you need on TV.”

He understands the concern and frustration expressed by the disabled community, he said. But Kevin McHale, 21, who plays Artie, excels as an actor and singer and “it’s hard to say no to someone that talented,” Falchuk said.

“Glee” isn’t alone in using an able-bodied actor for a wheelchair role: “Curb Your Enthusiasm” did it twice in a recent episode.

While TV has grown more inclusive of ethnic and gay characters, those with disabilities represent a sizable minority that hasn’t fared as well – whether with genuine or fake portrayals.

About one-fifth of Americans age 5 to 64 have a physical or mental disability – more than 50 million, according to U.S. Census figures. But fewer than 2 percent of the characters on TV reflect that reality, according to a 2005 study of Screen Actors Guild members conducted by researchers at the University of California, Los Angeles.

And it’s not a small playing field: There are 600 characters or more on the scripted comedies and dramas airing on the five major networks in a typical season.

More than a third of performers with disabilities reported facing discrimination in the workplace, either being refused an audition or not being cast for a role because of their disability, the study found. Many performers fear being candid about their health or needs to avoid pity or being seen as incapable of doing a job.

There can be added production expenses, said veteran casting director Sheila Manning, such as hiring a translator for a performer who is deaf.

“It costs a little more, but look at the positive reaction they’re (the networks) getting. I think that more than offsets the cost,” Manning said, adding that it’s the morally right thing to do.

And producers simply can’t complain of a shallow pool of choices.

“There are very talented performers with disabilities. … We just don’t know what producers are thinking,” said Gloria Castaneda, program director of the Media Access Office, a California state program that promotes hiring of the disabled in the entertainment industry. It also gives annual awards for positive portrayals.

The cause has union support: A campaign sponsored by three major entertainment guilds and aimed at creating equal employment opportunities for actors, broadcasters and recording artists just marked its first year.

TV’s past, oddly enough, was brighter. In the 1980s, actors with disabilities could be seen regularly in a variety of shows. They included Jewell, who costarred on “Facts of Life,” and James Stacy, who played a love interest for Sharon Gless on “Cagney & Lacey” and appeared in “Wiseguy” after losing limbs in a motorcycle crash.

R.J. Johnson, a writer and filmmaker, documented the golden period in “Breaking Ground.” Among those interviewed in the film was an actress who proclaimed, “We’re never going back. It won’t happen.”

Johnson says that “everything aligned” to encourage producers and directors such as Michael Landon (”Highway to Heaven”) to create characters with disabilities and then hire the right actors to play them.

“Then it kind of faded away,” says casting pro Manning. “It was a cause, and then it wasn’t.”

But she sounded a note of optimism, saying, “It’s in the public consciousness again, so it’s in the production consciousness.”

A friend was on the mind of Vince Gilligan, executive director of “Breaking Bad,” when the role of Walter Jr. was formed. Gilligan said he was thinking of a dear college pal, a man “with an infectious personality,” who died in recent years.

“It must have been I wanted to represent him in such a fashion when I created the character of Walter Jr.,” Gilligan told a recent industry forum on the hiring and portrayal of people with disabilities. “There was no reason for him to have cerebral palsy. It just seemed like, ‘Why Not?’ There’s no better reason than that, I suppose.”

More is at stake than actors’ careers, say advocates.

“When a person with a disability sees a positive image on TV that looks like them, their whole attitude changes. It gives them hope for what they can do in the future,” said Castaneda of the Media Access Office.

It counts for their families as well, said veteran writer Janis Hirsch, who works on Fox’s “Brothers” and “‘Til Death,” and who had polio as an infant.

“I am sick and tired of my son not seeing anyone even remotely like me on TV,” she said. “The first time my son saw someone use forearm crutches was the giraffe puppet in ‘Lion King.’ He was so excited. Where else do you see it? You just don’t see it.”