There has been no public reaction from Iranian authorities.
Sotoudeh was summoned to Iran's Intelligence Ministry on March 30, according to an account by her husband that was posted on his Facebook page, which Reza Khandan has used to keep his wife's supporters informed about her situation.
Khandan wrote that the summons was delivered during a trip to the province of Khuzestan.
"A few minutes ago, we were shopping in the bazaar of the city of Dezful when the Intelligence Ministry called and summoned Nasrin and our host in an illegal and impolite manner," Khandan wrote on Facebook on March 30. "They were told to present themselves to the Intelligence Ministry within an hour."
A few hours later, he wrote that because the summoning -- from the Dezful office of the Intelligence Ministry -- was done "illegally," via telephone, she decided to ignore it.
Instead, he said, the couple went horseback riding. He later posted a picture of himself and his wife on horseback.
In an interview with RFE/RL, Khandan explained more fully why Sotoudeh decided to ignore the call: "Lawyers have always said that summoning via telephone is illegal and no one should abide by those calls," Khandan said. "Summoning may only take place through the judiciary; it should be done via an official written summons."
The reason for the summons is not clear. It followed by just a few days the posting of a speech by Sotoudeh in which she referred to the Islamic republic as a "big prison" and which was shared on social media and news sites.
In the speech, Sotoudeh criticized the house arrest of Iranian opposition figures. "We seem to be free. But our heart is always, always divided between two groups -- those who are under arrest in their owns homes, [Zahra] Rahnavard, [Mir Hossein] Musavi, and [Mehdi] Karrubi, they are prisoners of conscience...[and] those who are serving their terms in prisons in different cities of Iran," she told a cultural gathering.
Sotoudeh is one of a small number of human rights lawyers who take on sensitive political cases in Iranian courts.
In her speech, Sotoudeh mentioned two colleagues -- Abdol Fatah Soltani and Mohammad Seifzadeh -- who have ended up in jail over their defense of political activists and students.
It is unclear when Sotoudeh made the speech. A video of her comments was posted online on March 28.
Sotoudeh was among a dozen political prisoners freed in September ahead of a trip by Iranian President Hassan Rohani to New York to attend the United Nations General Assembly. She was sentenced to 11 years in prison in 2010 after her conviction on a number of charges, including acting against national security. An appeals court later reduced her sentence to six years.
Her defense of activists, opposition members, and juvenile offenders on death row and her outspokenness are thought to be the reason for the state pressure she has been facing.
While in prison, she refused to be silenced. She reportedly launched several hunger strikes to protest her condition and alleged state harassment of her family.
Sotoudeh and dissident Iranian filmmaker Jafar Panahi were awarded the European Parliament's Sakharov prize for Freedom of Thought in 2012.
To many Iranians, Sotoudeh, a mother of two, has become a symbol of resistance against repression in their country.