Repeated and increasingly flagrant abuses have brought the docu-drama into disrepute, but theres no reason to consider the form intrinsically corrupt. After all, "Citizen Kane" was sort of a docu-drama, wasn't it? Not a bad little movie, either.

Tonight, CBS redeems the honor of the television docu-drama with "A Death in Canaan" (Channel 9 at 9 o'clock), an extremely powerful and properly distressing adaptation of the Joan Barthel book about Peter Reilly, a New England teen-ager convicted of murdering his mother.

How unerringly faithful the script is to the book becomes unimportant because the film remains movingly true to the point and purpose of Barthel's exhaustive reportage: that justice does not always triumph and that the legal system is perilously fallible.

"People work," says the barthel character in the closing minutes of the program. "People - not the system." This is a heavy message for a society in which machines and bloated bureaucracies take ever-expanding roles.

Although Reilly was found guilty by a court of law and, indeed, by a machine - the lie detector, or polygraph - the people of Canaan, Conn., believed him to be innocent. In the course of proving the court and the machine wrong, they put something of their lives, fortunes and sacred honors on the line, and in winning after a long and costly fight, they scored a sizable victory for the individual against the system.

The script, by Thomas Thompson and Spencer Eastman, was directed by British filmmaker Tony Richardson ("Tom Jones"), his first American television film, and Richardson's meticulous approach lifts "Canaan" well beyond the level of the usual TV moive. He has managed to be both straight-forward and graceful, so that the story is told with a minimum of melodramatics yet maximum impact.

Richardson's finest scence is probably the film's longest: the interrogation of the boy by the man with the lie detector. Old Sgt. Scully operates on the assumption that machines, unlike people, cannot lie; slowly and methodically he leads the boy to the point at which the difference between reality and fantasy in the kid's own mind becomes a blur.

The scene is triply effective because of the way it was shot by Richardson and because Kenneth McMillian, as Sgt. Scully, is so relentlessly effective in his performance. The sergeant could have been an easy heavy, a mere villian, bu we are allwed to perceive that he may be as much a victim as the boy is.

Rarely does any piece of television take one through such varied emotional territory - from suspense over the interrogation and trial to anxiety over the outcome to exhilaration when the decision is finally reversed through the dedication of the townspeople.

Richardson is a fastidious guide through this ordeal, and he knows how to reach us emotionally without pulling out gratuitous stops. After the verdict, when some of the townspeople have ended a day of work on the boy's behalf, they join him for a relaxed evening and, at one point, softly sing "Blowin' in the Wind" while he plays the quitar.

There will not be a dry eye in the country at this point: it's a magnificently affecting moment.

There are other small signs of a wise director at work; one of the smallest is a simple pan out a court-room window. Inside, the judge, jury, lawyers, onlookers and the 18-year-old accused of matricide are listening to a taped description of the brutally assaulted body he discovered. Outside, Richardson shows us a small crowd of children playing a children's game, oblivious to the life and death struggle going on inside the building.

Among liberties taken with "A Death in Canaan," is the casting of glamorous Stefanie Powers as author Barthel, whom she resembles about as much as Suzanne Somers does Gertrude Stein. On the other hand, Paul Clemens, the young actor who plays Reilly, is much shorter and dumpier than Reilly is, but this hardly matters since ths kid's performance is shatteringly convincing.

The film was screened in New York last month for the real residents of Canaan, the "People Behind Reilly" who sold buttons and homemade brownies to help pay for his attorneys, and they watched largely in silence as they saw themselves portrayed by actors and their town portrayed by Eureka, Calif., where "Canaan" was filmed.

The article by Barthel that made Reilly's case one that attracted national attention and the interest of numerous literary celebrities was originally published in New Times magazine, and the Canaan audience laughed loudly when a character in the film describes the magazine as "a little too intellectual for local tastes."

Reilly himself was there, in a three-piece corduroy suit, shaking hands with Clemens and saying he thought the film a good one. Undoubtedly some inaccuracies, exaggerations and distortions have set in. In fact, exposition becomes rushed and awkward during the last half-hour of the film, probably because Richardson spent so much time on the interrogation and trial scenes.

Most of the creative decisions appear to have been with great care and intelligence, however, and in the end this story that documents terrifying vulnerabilities within our legal system - and symbolically, within all social systems under which we try to live- becomes a stirringly inspirational shout on behalf of hope. 'Count Dracula'

Old vampires may never really die. The longevity of Bram Stoker's Count Dracula character would seem to prove it. In recent years the old boy has been flapping at the window in such vehicles as Anne Rice's novel "Interview with the Vampire" and the Broadway play "Dracula" with Frank Langella. Currently there are also an off-Broadway play and a small-scale L.A. musical in which that mordacious man-about-necks figures prominently.

Public television makes room for at least one more tonight with an elegantly eerie and erotic "Count Dracula," to be seen in three weekly one-hour installments (Channel 26 at 10 p.m.).

Subtitled "A Gothic Romance Based on Bram Stoker's 'Dracuia,'" Gerald Savory's script keeps a straight face as it treads the treacherous realm between a heavy-handed Hammer approach and artsy-shmartsy poses. There are whispered allegorical over-tones, but basically Savory is content to tell the story, and tell it as crisply and creepily as possible.

Director Phillip Seville keeps the atmosphere freshly charged with dread and is invaluably assisted in this by the visual effects of Tony Harding. "You've cut yourself," the count says to a houseguest and suddenly - zing! - there's a flash to a solarized view of that inveterate fiend's blood-hungry eyes.

Shock effects are clearly kept secondary, however, to the maintenance of a rich and pervasive perversity. Scenes of the caped Count flapping desperately up the walls of his castle - the stricken addict who cannot overcome nasty habits - have a wonderfully ghastly quality that recalls, among other things, the hideous henwoman who was the visual kicker to "Freaks."

The Dracula tale really is a humdinger when it comes to objectifying evil and making it manageable albeit with great difficulty. The story plays adroitly on three primal fears: the fear of death, the fear of sex and the fear that the first two fears are actually the same one. This coproduction of the BBC and WNET in New York exploits these fears with flourish and spirit, and Louis Jordan's performance as the title fiend is stylish and subtle. It's quite an accomplishment for the man who sang "Gigi" and does commercials for florists.

"Count Dracula" could become one of the biggest crowd pleasers in the history of public television.

'Goldie' 'Goldie'

"Count Dracula" concerns a blood-slurping ghoul. "A Death in Canaan" begins with the discovery of a mutilated corpse. So how does Goldie Hawn's musical special on CBS manage to seem the nights most morbid television program?

"Goldie," a pompous romp at 8 o'clock on Channel 9, trots out the inoffensively perky Hawn for an hour that is very stingy with the much-advertised guest stars - George Burns, Shaun Cassidy, John Ritter, the Harlem Globetrotters - but insidiously generous when it comes to revealing the with and wisdom on the star, both of which are in the marginal range.

"I think it's important to keep in touch with the child in yourself," says Goldie. "We need something old-fashioned in our lives," Goldie says. "I think of the '60s as the good old days . . . People were so involved then," Quoth the Maharajinette.

Whether producer George Schlatter's or writer Digby Wolfe's, it was a true brainstorm to have the Globetrotters sing "Short People" at Goldie as she flits around the basketball court. This is cuteness maximus and genuinely jolly.

But when Burns swoops down on a cardboard moon, you know it will only be milliseconds before his lousy movie "Oh, God" is plugged for the umptillionth time, and it is. With Ritter, Hawn trudges through a lampoon of Hollywood fatuousness, which seems pretty cheeky in a program that plugs the living daylights out of everything from Ritter's "Three's Company" to a movie Hawn made with Chevy Chase that won't even be released until July.

In these days of financial and sexual scandal, anyway, affectionate spoofs of Hollywood ("income high, morals low") seem disingenuous at best and later, when Goldie does the cool jerk near a picture of Golda Meir during her salute to the '60s, even the most forgiving connoisseurs of bad taste are likely to wince.

The dynamite act is the finale, when Hawn joins Shaun Cassidy for a far-too-brief duet. Here we have two of the reigning silly sex objects of American side-by-side - Mr. and Ms. Nynph - and the electricity between them is utterly disarming. Director Don Mischer unfortunately missed the point entirely, however, and keeps trying to avoid the pair by doing as much abrupt cutting and gimmicky camera work as he can.

Goldie Hawn made a name by pretending to be everybody's fool on "Laugh-In." The "Goldie" special makes one wonder just how much of that was pretending.