Ralph Silvestro, a legal clerk who works at the Criminal Justice Center in Philadelphia, never imagined that anyone would have a beef over the American flag he had taped to the side of his work computer.

After all, he works in a courthouse.

To Silvestro, who served in the Navy for six years and in the Air Force Reserve for another six, the miniature American flag affixed to his computer was a symbol of his patriotism, he said.

For months, that flag and another one that Silvestro had taped to his computer - a black "pirate" flag with skull and crossbones - greeted a steady stream of folks, mostly lawyers, who lined up daily at the front counter of the court's Active Criminal Records department to file motions that Silvestro processed.

No one complained about the flags, Silvestro said.

Then on Sept. 23, Silvestro got an e-mail from his supervisor:

"Keith has advised me as your supervisor, that the flags must come down. They are not appropriate for the workplace," the e-mail said.

The "Keith" mentioned in the e-mail was Keith Smith, the new director of Active Criminal Records.

Silvestro, 34, said he could understand why Smith didn't want him to display a pirate flag - a symbol of thievery on the high seas - in a criminal courthouse. The flag was a gift from a co-worker who had bought it while on vacation and knew that Silvestro liked pirate stories and had served in the Navy, Silvestro said.

But Smith's ban on the American flag just burned Silvestro's butt, he said.

"I served this country for 12 years. I could have died for this flag, but I can't hang it up. What's up with that? I don't understand," Silvestro said in an interview earlier this week.

Silvestro added: "For me, this is about my rights being taken away from me in a building where your rights are supposed to mean more than anything."

Smith did not return two phone calls from the Daily News yesterday.

When asked if Smith had violated Silvestro's constitutional rights, perhaps infringing on his freedom of expression, a civil-rights lawyer said: "No."

"Here's the thing: Your boss rules your life," said Mary Catherine Roper, a staff attorney with the American Civil Liberties Union of Pennsylvania's Philadelphia office. "Your employer gets to make the rules."

As long as Smith applies the same rules to everybody evenly, meaning no staffer is allowed to display the American flag at the public counter, Smith is on solid legal ground, Roper said.

"People really have no idea how much control they have to give up when they go work," Roper said. "Workers generally don't have a lot of rights."

Even so, the episode has outraged many of Silvestro's customers. And, being lawyers, they didn't mince words.

"It has me so ticked off," said lawyer Rania Maria Major-Trunfio. "It's absolutely ridiculous"

Silvestro, who grew up in South Philly and wears his jet-black hair slicked back in a ponytail and talks in a rapid-fire staccato, is a colorful figure in an otherwise sterile space. Major-Trunfio said she immediately noticed that the flags were gone and asked Silvestro about them.

"It offends me that he had to take the American flag down," she said. "Not enough people feel a real strong sense of patriotism for our country and, quite frankly, if someone is going to be upset that an American flag is in the courthouse, then America is really in a sad place."

Silvestro said he talked with Smith after receiving the e-mail from his supervisor. Smith told him that he wanted to keep the front counter looking clean and uniform, according to Silvestro.

"I kept telling him, 'I don't understand. It's the American flag. Who is it bothering? Who is it offending?' " Silvestro recalled. "He said, 'You can hang it up at the back of your desk and it has to be kept out of sight.' I was really furious and hurt."

Major-Trunfio said she walked up to the motions counter yesterday and her eyes widened when she saw the Christmas lights, garland and small fake tree.

"I'm like, 'How come you get to put Christmas decorations up, but you can't put the flag up?' " Major-Trunfio asked. "The female clerk just looked at me and said, 'You're funny.' "