As senator, Miriam became an ally of President Joseph Ejercito Estrada, a former movie actor. He was impeached by the House of Representatives, and tried by the Senate as an impeachment court. Miriam was the only one of 24 senators who had served in the judiciary. As a former trial judge, she insisted that Estrada should be granted due process of law. Instead, the impeachment trial was never concluded and Estrada, like Marcos, was overthrown by another People Power revolution which installed President Gloria Macapagal Arroyo, an economist.

Under a new administration, Miriam ran on the Estrada opposition ticket, and again led during the early days of the canvass of votes. But eventually, her votes were whittled down, and it appeared that she was again cheated in the elections. By this time, Estrada was already in detention as the accused in a plunder case.

In the next elections, Estrada handpicked another movie actor to run for president. Miriam objected, and instead ran for senator under President Arroyo’s ticket. In 2004, Miriam won her second term as senator. She chairs two powerful committees: the energy committee, and the foreign relations committee.

She is also one of President Arroyo’s most trusted legal advisers. In late 2006, a group of young lawyers nominated her for Chief Justice of the Supreme Court. But she reportedly gave way to the senior associate justice, saying that she was too young for the post.