Islamic influence in Egypt's governance is the most inflammatory issue following last year's ousting of longtime President Hosni Mubarak. Islamists have swept elections since then, and the Brotherhood's Mohammed Morsi is the president—but the Brotherhood faces criticism from even more stringent Islamists as much as from liberals.
Ultraconservatives known as Salafis have pushed for firm language in the new constitution to ensure implementation of Shariah, even calling for demonstrations on Friday. Top Salafi clerics threatened to rally voters against the constitution when it is put to a vote in a referendum before end of this year, if their demands are not met.
Together, Salafis and the Brotherhood dominate the 100-member assembly writing the new constitution.
The controversy centers on the phrasing of key articles that expand the role of Islamic Sharia laws.
The previous constitution said "the principles of Shariah" are the basis of law in Egypt. Liberals favored such phrasing, which they say allows greater leeway, meaning legislation can meet the broad ideas of Islam.
Salafis wanted that changed to "the rulings of Shariah," implying Egypt's laws would have to abide by the strict letter of what clerics say is meant in Islamic law.
Liberals fear that could bring heavy restrictions on many rights and would forge a new role for religious scholars similar to clerical rule in Iran.
In its statement, the Muslim Brotherhood appeared to try to accommodate liberals' demands by keeping the phrase "principles of Shariah," while adding an article explaining what that means: the principles would include "the juristic rules" of Shariah agreed upon by scholars and the "accepted sources" of the Quran's interpretation.
Yousseri Hamad, spokesman of Al-Nour party, the most popular political arm of the Salafi movement, commented on the phrasing by saying, "this satisfies us and we agree on it."
Critics fear such wording could make it easier for hard-liners to challenge laws they feel don't adhere to Shariah and empower legislators to pass laws that could impose heavy-handed limits on freedoms of expression, worship, faith and other civil liberties.
The Muslim Brotherhood repeated its stance that the Shariah penal code should not be implemented for now by saying that the penal code determines punishment according to the crime after "preparing society first to understand Shariah and accept it." However, it is not clear who would decide on when society would be ready for Shariah punishment for crimes, and such vague phrases spark more concerns.
Many Egyptians fear the implementation of Islamic penal code as they watch neighboring Saudi Arabia punishing people convicted of murder, drug trafficking, rape, adultery and armed robbery with execution, usually with a sword, cutting off limbs or stoning to death.
The Brotherhood also defended its hard-line position on an article related to women rights.
The proposed article, supported by the Brotherhood and Salafis, states that "women are equal to men without violating the laws of Islamic Shariah." Liberals and rights advocates fear that would enable Islamist legislators to pass laws that violate women's rights, such as lowering the age of marriage or permitting female genital mutilation.
A new constitution would be a key step in establishing a democracy to replace the Mubarak's regime, ousted last year in an uprising led by progressive, secular activists.
But in the nearly 20 months since then, Islamists have emerged as the strongest political force. Morsi was elected president after the Brotherhood and the Salafis swept parliamentary elections, leaving the liberals with minimal representation. The parliament was later disbanded.
The panel drafting the constitution said it could be ready for public discussion as early as the first half of November. The new constitution then would have to be put to a public referendum within 30 days.