The California affiliate of Planned Parenthood, embroiled in controversy over the release of undercover video footage of employees purportedly discussing the price of fetal tissue from abortions, has filed a lawsuit against the anti-abortion organization that released the videos, a series of Tweets showed Thursday. The Center for Medical Progress released a series of videos this summer, which have been debunked by some, that they said showed Planned Parenthood was engaged in the illegal sale of tissue from aborted fetuses to companies for research.

“We’re holding anti-abortion extremists accountable for their three-year conspiracy to attempt to shut our doors,” Cecile Richards, president of Planned Parenthood Federation of America, wrote on Twitter Thursday.

In Planned Parenthood’s first offensive move against the Center for Medical Progress, the reproductive health nonprofit said members of the anti-abortion group violated state and federal law, the Hill reported. One of the laws Planned Parenthood said the group broke was a ban on secret taping with unlawful purpose.

Since the recordings were made public, reproductive health clinics have recorded an increased number of threats. In November, a man walked into a Colorado Planned Parenthood clinic and killed three people, saying he attacked the facility because Planned Parenthood was “murdering little babies,” CBS News reported.

Legislation led by Republicans was passed in Congress to defund Planned Parenthood, but President Barack Obama vetoed the effort last week, the New York Times reported. Obama said at the time taking funding away from an organization that also acts as a major healthcare provider to women would impact low-income people in a disproportionate way.

After the release of the second video, Planned Parenthood criticized the Center for Medical Progress, saying it does not sell fetal tissue for research but collected fees for shipping. Selling fetal tissue is illegal.