A federal judge has dismissed a Texas girl's objection to locator chips in student ID badges at a public high school in a case that raises concerns about the erosion of privacy and civil liberties.

Andrea Hernandez, 15, and her father told school officials they oppose the use of locator chips on religious grounds.

Officials at San Antonio's Northside school district said they were willing to give her a chipless badge, but warned the straight-A student she would be expelled from her prestigious selective-enrollment school if she did not wear it.

Hernandez refused, saying the new badges are the "mark of the beast" and that to be made to wear one equates to forcing her to "fall in line" and endorse the program.

Judge Orlando Garcia denied her request for an injunction preventing the district from sending her back to the neighborhood school in a 25-page ruling Tuesday.

"In today's climate, one would be hard pressed to argue that the safety and security of the children and educators in our public school system is not a compelling governmental interest," he wrote.

"The accommodation offered by the district is not only reasonable, it removes plaintiff's religious objection from legal scrutiny all together."

Her refusal to wear even a chipless badge was "clearly a secular choice, rather than a religious concern," the judge added.

Hernandez's lawyers have vowed to appeal, arguing that requiring her to wear the badge equates to unconstitutional "forced speech" and that it isn't a judge's place to second guess someone's religious views.

"The issue in the case is whether or not people who disagree with these programs on religious or constitutional grounds can opt out," said John Whitehead, president of the Rutherford Institute civil liberties group helping Hernandez pursue the case.

"I'm concerned about the country when we see this compliant complacency being forced on people."

Similar tracking programs are being implemented at schools across the nation. While they can help officials locate students in an emergency, Whitehead said the prime motive is money.

Schools are awarded funds based upon attendance and the chips allow administrators to count students as present even if they don't make it to their homeroom because they're chatting in the hallway with a friend.

The district said it is spending about $261,000 on a pilot program at two schools and expects to realize $2 million in additional revenues.

It could expand the program to its 110 other schools if successful.

First developed to help track goods, radio frequency identification technology is increasingly being used for surveillance, Whitehead said.

The southern US state of Virginia is currently considering inserting locator chips into vehicle license plates.

"Wherever you go, there's no privacy," Whitehead told AFP. "If you're an alcoholic and you want to go to an Alcoholics Anonymous meeting, (the government will) know you're there."

The American Civil Liberties Union also objects to the use of tracker chips on students, which it characterizes as the "perfect stalking device."

"Because the technology is easy to acquire, it is vulnerable to hacking, which could allow someone outside the school to monitor a student's off-campus whereabouts if they obtained the student's tracking number," said Dotty Griffith, director of public education for the ACLU's Texas chapter.

"In school, students' movements can also be monitored, not just their presence at school. Is it the school's business when students go to the restroom or with whom they sit in the school cafeteria?"

Northside is the fourth largest school district in Texas, serving about 100,000 students in 355 square miles (920 square kilometers).

In a letter to parents, it explained that it was launching the tracking program at Jay high school and Jones middle school in September "as a means for increasing the safety and security of our students."

"We want to assure you that the 'smart' ID cards store no personal information, and the 'smart' ID card does not work outside of the school," the school district wrote.

Since the ID badges are also used to purchase food in the cafeteria, check books out of the library and participate in after school programs, Hernandez was denied access to many school activities.

She couldn't even vote for homecoming queen, Whitehead said.

Tracking students isn't just an American phenomenon. Schools in Brazil began placing chips in the uniforms of thousands of students last year in an effort to cut down on truancy by sending text messages to parents if a child is late for class.