According to the BBC, police held back a group of 1,000 counter-demonstrators who surrounded the women in Kabul Wednesday, some throwing stones and shouting "Death to the slaves of Christians!"
The new law was passed by parliament and signed in March by President Hamid Karzai, who is up for reelection this year. According to media reports, it includes a provision that requires women to obtain their husband's permission for activities outside the home.
Most controversial is a clause that says "a wife is obliged to fulfill the sexual desires of her husband" and that a husband can demand sex with his wife every four days -- restrictions some have equated to opening the door to marital rape and harkening to the type of harsh rules imposed during the Taliban era.
Several members of the international community have roundly condemned the legislation, which applies only to the nation's Shia minority, who make up less than 20 percent of the population.
Karzai has been accused by some of supporting the legislation to win the favor of Shiite clerics who introduced it.
The United Nations and Secretary of State Hillary Clinton and are among those who have voiced criticism of the law. President Barack Obama called it "abhorrent" at a press conference in Europe for the NATO Summit.
Although he insists that Western governments have misunderstood the restrictions, Karzai recently ordered his justice minister to review the law and said that it would not be enforced until a ruling is made. Afghanistan's constitution states that men and women "have equal rights and duties before the law."
One marcher in Wednesday's protest, Fatima Hussein, 26, told the New York Times: "Whenever a man wants sex, we cannot refuse. ... It means a woman is a kind of property, to be used by the man in any way that he wants."
In a statement calling for the Afghan government to repeal the law, Human Rights Watch Asia director Brad Adams said, "Any deals with the Taliban and other fundamentalist groups should not be at the expense of women's rights."
"What small gains that have been won by women in Afghanistan must not be up for negotiation," he added.
Ayatollah Mohammed Asef Mohseni, one of the clerics behind the law, told Reuters that some of the measure's provisions are intended to "encourage men to have more interest in a social and personal life with his wife."
Mohseni also said that if women want more freedom, they can ask for it to be included in their marriage contract: "If he says no, she can marry someone else."
"Without proper reading people make their own opinions about the law, which I really regret," he told the news service.
Supporters say the so-called restrictions actually protect women and many have accused the protesters of ceding to the wishes of foreign governments who run counter to Islamic philosophy. Wednesday's counter-demonstrators were of mixed gender but international observers noted that many of them were women.
Anand Gopal, the Christian Science Monitor's Afghanistan correspondent, says there is a distinct difference in the backgrounds of the protesters who oppose the law and the larger group of female counter-demonstrators who support it. The 300 protesters were mostly urban, educated women, many of whom work for NGOs or international organizations. They are the women who have made the most gains with intervention from the Western world and the U.S. presence in Afghanistan.
But Afghanistan remains a largely rural society, where Afghan women who live in a countryside controlled by patriarchal tribes have seen little change, and the war has led to increased violence in their communities.
For many women, restricted access to education, financial independence and domestic violence are already an entrenched part of their reality. Gopal says that for the majority of Afghan women, "Most have never heard of the law and the few that have, they kind of say, 'Well this is how life is anyway.'"
"Women tend to support the law because it jives with the version of Islam that they've been taught. Many of these women have never been outside their village ... it's everything that they know," Gopal said.
"This would be a radically different lifestyle for them if they were to start going outside of the home," he added.
Gopal also says that rural societies have a much more communal view of life that contrasts with Western individualism. For example, if a woman is allowed to leave the home by herself and is raped outside of it, it becomes a problem for the whole family.
Furthermore, much of the Afghan population is suspicious of international influence upon their communities, and one misconception about the protesters is that they were paid by anti-Muslim foreigners to act against the law. On Wednesday, counter-demonstrators shouted chants like "We want Islamic law!" and other renunciations of Western influence, reported the New York Times.
According to Gopal, the challenge for the United States and other nations involved in Afghanistan is to figure out a way to increase credibility amongst the rural population but, "There's no real easy way to do that."
He suspects that President Karzai, who is pulled in many directions from the United States, other nations and conservative members of his own parliament, will probably lay low for a few months and quietly repeal the law when public uproar has died down.
Abbas Noyan, a Shiite lawmaker who opposes the law, told the Associated Press he is hopeful it will be changed. But others are less sure, and even the country's minister of women's affairs, who is female, has declined to comment on the legislation thus far.