Mansureh Shojai, Talat Taghinia, and Farnaz Seifi were arrested at a Tehran airport on January 27, said Bamdad Davudi, Shojai's son.
He said Nobel peace laureate and lawyer Shirin Ebadi will be representing the detainees.
The three women were involved in a recent campaign dubbed "One Million Signatures," which aims to change Iran's "discriminatory laws" for women.
They sought to collect signatures both online and in person.
RFE/RL Iran Report
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