A federal judge Friday dismissed a lawsuit brought by members of the U.S. military against the U.S. Department of Defense that sought to make an anthrax vaccine optional rather than mandatory.

Judge Rosemary M. Collyer said the Food and Drug Administration made no mistake in approving the vaccine as safe.

"The FDA applied its expertise and found the vaccine is effective. The FDA did not act arbitrarily or capriciously. ... The court will not substitute its own judgment when the FDA made no clear error in judgment," Collyer wrote in her ruling, according to CNN.

The dispute around the vaccine started years ago, when a federal judge suspended the vaccination program in 2004 after faulting the FDA’s process for approving the drug. After the FDA redid the process and declared it safe, the military announced plans to reinstate mandatory vaccinations.

This decision led to a lawsuit by eight military members, Thomas Rempfer, Joshua Cohen, Gareth Harris, Kevin Ferrara, Shameka Edwards, Eric Gearhart, Michael Palmer, and James Hailstone who argued the vaccine should be optional.

The lawsuit was filed against the FDA, the Department of Health and Human Services and the Pentagon and it’s the third of its kind and the latest chapter in a dispute that had been going on for at least six years.

The Pentagon continues to require the vaccine, saying the program is necessary to protect soldiers against biological attacks.

"We owe it to our service members to give them every possible protection. Force protection is the number one priority in the Defense Department and the anthrax inoculation program is an important force-protection measure,” Pentagon spokesman Bryan Whitman said quoted by the same source.

The decision was welcomed by the FDA as well. “The FDA has repeatedly found, and independent medical experts have confirmed that anthrax vaccine is safe and effective” said FDA’s representative Heidi Rebello.

Anthrax, one of the most dangerous biological agents, is a bacterial disease whose spores can cause infection through inhalation, ingestion or skin contact. According to the federal Centers for Disease Control and Prevention, antibiotics are used when symptoms are detected, but inhalation anthrax has an estimated fatality rate of 45 percent to 90 percent.

The vaccine against anthrax -- marketed by the trade name BioTrax -- is licensed to be given in a six-dose regimen over nearly 20 months.