Maria Corazon "Cory" Cojuangco Aquino (born Sumulong; January 25, 1933 - August 1, 2009) was a Filipina politician who served as the 11th President of the Philippines and the first woman to hold that office. She is widely accredited as the Mother of Asian Democracy. The first female president in the Philippines, Aquino was the most prominent figure of the 1986 People Power Revolution, which toppled the 21-year authoritarian rule of President Ferdinand E. Marcos and restored democracy to the Philippines.
Agrarian reform
President Aquino envisioned agrarian and land reform as the centerpiece of her administration's social legislative agenda. However, her family background and social class as a privileged daughter of a wealthy and landed clan became a lightning rod of criticisms against her land reform agenda. On February 22, 1987, three weeks after the resounding ratification of the 1987 Constitution, agrarian workers and farmers marched to the historic Mendiola Street near the Malacanan Palace to demand genuine land reform from Aquino's administration. However, the march turned violent when Marine forces fired at farmers who tried to go beyond the designated demarcation line set by the police. As a result, at least 12 were killed and 51 protesters were injured in this incident now known as the Mendiola Massacre. This incident led some prominent members of the Aquino Cabinet to resign their government posts.  In response to calls for agrarian reform, President Aquino issued Presidential Proclamation 131 and Executive Order 229 on July 22, 1987, which outlined her land reform program, which included sugar lands. In 1988, with the backing of Aquino, the new Congress of the Philippines passed Republic Act No. 6657, more popularly known as the Comprehensive Agrarian Reform Law". The law paved the way for the redistribution of agricultural lands to tenant-farmers from landowners, who were paid in exchange by the government through just compensation but were also allowed to retain not more than five hectares of land. However, corporate landowners were also allowed under the law to "voluntarily divest a proportion of their capital stock, equity or participation in favor of their workers or other qualified beneficiaries", in lieu of turning over their land to the government for redistribution. Despite the flaws in the law, the Supreme Court upheld its constitutionality in 1989, declaring that the implementation of the comprehensive agrarian reform program (CARP) provided by the said law, was "a revolutionary kind of expropriation".  Despite the implementation of CARP, Aquino was not spared from the controversies that eventually centered on Hacienda Luisita, a 6,453-hectare estate located in the Province of Tarlac, which she, together with her siblings inherited from her father Jose Cojuangco (Don Pepe).  Critics argued that Aquino bowed to pressure from relatives by allowing stock redistribution under Executive Order 229. Instead of land distribution, Hacienda Luisita reorganized itself into a corporation and distributed stock. As such, ownership of agricultural portions of the hacienda were transferred to the corporation, which in turn, gave its shares of stocks to farmers.  The arrangement remained in force until 2006, when the Department of Agrarian Reform revoked the stock distribution scheme adopted in Hacienda Luisita, and ordered instead the redistribution of a large portion of the property to the tenant-farmers. The Department stepped into the controversy when in 2004, violence erupted over the retrenchment of workers in the Hacienda, eventually leaving seven people dead.

Q: What is the most important Agrarian reform by Corazon Aquino ?
A: President Aquino envisioned agrarian and land reform as the centerpiece of her administration's social legislative agenda.
What is an example of a law she passed or a reform she was involved in ?
In 1988, with the backing of Aquino, the new Congress of the Philippines passed Republic Act No. 6657, more popularly known as the Comprehensive Agrarian Reform Law".
In 1988, with the backing of Aquino, the new Congress of the Philippines passed Republic Act No. 6657, more popularly known as the Comprehensive Agrarian Reform Law".