Henry E. Hudson, Arlington County's commonwealth's attorney, has experienced the Arlington criminal justice system from numerous angles -- as a deputy sheriff in 1969, as a bailiff, and as assistant commonwealth's attorney. There was never much doubt in his mind about which side of the courtroom he wanted to occupy.

"I just, quite frankly, prefer to represent the prosecution. I feel more comfortable on that side of the case," he said in a recent interview.

Hudson has represented the prosecution in Arlington since 1979, when, at age 32, he won election against his former boss to become the Washington area's youngest local prosecutor.

Since then, Hudson, a Republican in what is a largely Democratic courthouse, has earned the praise of police and some citizens for an energetic crackdown on massage parlors and adult bookstores, a reduction in plea bargaining and an increase in jail sentences of convicted burglars.

But he draws fire from attorneys who say he is relentless, rigid and bent on bringing his conservative moral standards into the courtroom.

"Hudson is a very hard worker who cares about his job, is accessible to defense attorneys in terms of conferences and returning telephone calls," said defense attorney John Youngs. "My main gripe about Henry is his philosophy of justice . . . it seems to me he's not interested in very evenhanded justice. He knows which cases a jury will hammer a client on and he won't waive a jury in those instances. In plea bargaining, he takes a very hard line and, I think, an insensitive approach to justice in requiring incarceration much too frequently."

The controversial, emotional subject of pornography, and the underlying questions of what is obscene and who is to decide what is obscene, are the targets of the sharpest criticism of Hudson.

Dennis Sobin, publisher of the sexually oriented newspaper Free Spirit, says he was not surprised to learn Arlington prosecutor Hudson was heading a national commission on pornography.

Sobin, a frequent object of Hudson's ire, says Hudson, the commonwealth's attorney with the "no-nonsense" reputation, was an obvious choice. "The whole commission really has the tone of being a kind of prosecutorial body. It is putting sexual materials on trial," Sobin said.

Sobin, as well as more circumspect defense attorneys, say the crackdown on pornography in Arlington -- which peaked several years ago but still surfaces in occasional police seizures of X-rated videotapes and sexually explicit magazines -- treads the borderline of censorship and turns the prosecutor's office into a judge of what the county may see and read.

Two weeks ago, Circuit Court Judge Benjamin N.A. Kendrick dismissed a charge of distributing obscene material against Sobin, saying that his newspaper was not obscene, and ordered police to return 21 Free Spirit vending machines seized this spring.

Sobin's attorney, James Lowe, maintains that Free Spirit and other Sobin publications are essentially political, not erotic, adding that "the idea that anyone has a God-given right to tell you what to read is nonsense."

" Hudson was elected to prosecute criminals, not to judge books and magazines by his personal standards," said attorney Peter Baskin.

Hudson says he is not trying to write standards of obscenity for Arlington, maintaining that the prosecutions of Sobin and of businesses who rent X-rated videotapes are prompted by citizen complaints.

"Every time one of Sobin's magazines goes out, I get 12, 13, 14 phone calls from citizens complaining about it," he said. "The very clear message I get from citizens of Arlington County is that they don't like this kind of material in our community."

"Over the course of the years, there have been a number of prosecutions involving pornographic literature. I have a pretty good idea, based upon those cases, a pretty good impression of what is and is not acceptable'' in Arlington, he said.