DETROIT — A federal judge dismissed some charges Tuesday against eight people — including two doctors — in the genital mutilation of nine girls at a suburban Detroit clinic, finding it's up to states rather than Congress to regulate the practice.

U.S. District Judge Bernard Friedman dismissed mutilation and conspiracy charges against Dr. Jumana Nagarwala, who performed the surgery, and Dr. Fakhruddin Attar, who allowed his clinic in Livonia, Michigan, to be used for the procedure.

The same charges were dismissed against Attar's wife, Farida, and Tahera Shafiq, who assisted in the procedure, as well as four women who took their daughters to the clinic.

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Four of girls are from Michigan; the others are residents of Illinois and Minnesota.

"Congress overstepped its bounds by legislating to prohibit (female genital mutilation)," Friedman wrote in a 28-page opinion.

Michigan was the 26th U.S. state to officially ban the practice, also known as female circumcision or cutting. The state law was passed a few months after Nagarwala's April 2017 arrest. Female genital mutilation has been condemned by the United Nations, but is common for girls in some parts of Asia, Africa and the Middle East.

Nagarwala said she performed a religious custom on girls from her Muslim sect, the India-based Dawoodi Bohra.

She still faces conspiracy to travel with intent to engage in illicit sexual conduct and obstruction charges. Others in the case face obstruction charges.

"I did think he would rule in our favor," defense attorney Shannon Smith said of Friedman.

Smith filed a motion on behalf of Nagarwala to have the charges dismissed.

"When I first started researching, I was not sure how strong (the motion) would be, but I became more confident this would be the right result," she said.

A spokeswoman said Tuesday that the U.S. attorney's office was reviewing Friedman's opinion.

Smith said that if the ruling is appealed that "we're hoping the Court of Appeals and Supreme Court agree that the 1996 law was unconstitutional."

Mariya Taher, a social activist and FGM survivor, told the Detroit Free Press "this is crazy" and fears the ruling will put more women at risk.

"Unfortunately, this is going to embolden those who believe that this must be continued ... they'll feel that this is permission, that it's OK to do this," she said.

FGM in the U.S.

At the beginning of 2017, the U.K. had invited U.S. authorities to observe its border safeguarding program, Operation Limelight, which deploys officials to ports like Heathrow on specific dates, usually around school breaks, when families may be transporting their children in or out of the country to undergo FGM. After observing the British program, the United States created its own, calling it Operation Limelight USA, which it rolled out at airports across the nation. The two countries are now pledging to work even more closely together to tackle the issue.

"This is about protecting American girls," Mark Shaffer, chief of ICE's Homeland Security Investigations (HIS) Human Rights Violators and War Crimes Center, told CBS News. "It's happening in communities where it's a very closely guarded secret. It's happening to girls right underneath our noses."

Part of the issue for both countries is a lack of intelligence: It's very difficult for authorities to gather information about where, when, and by whom FGM is being practiced. When FGM does occur — for example, when families arrange for their young daughters to undergo the practice -- people often travel out of the country, making reliable intelligence gathering and intervention that much more difficult.

Haley Joelle Ott contributed to this report.