While Saddam Hussein remained in power as president of Iraq, Al-Mayah called for elections. Because of this, he was imprisoned. He was released from prison, partly because one of his former students was one of the interrogators.
Following the 2003 US invasion of Iraq, Al-Mayah was against both the occupation and the previous dictatorship.
According to Dr Talal Nathan al-Zuhary, director of the Mustansiriya University library, Al-Mayah believed that one day he would be bumped off by the Mossad or the CIA and that More recently [following the invasion], he was more worried about the looters who came after the regime fell and stole so much..
Al-Mayah became well-known as a human rights and pro-democracy campaigner.
On the evening of January 18, 2004, on the television channel al-Jazeera, he had criticised what he called the corruption of the Iraqi Governing Council (IGC), appointed by the US authorities, and demanded universal elections as soon as possible, as had earlier done during the presidency of Saddam Hussein. He is quoted as saying:
Since US authorities were planning a caucus system for choosing a new government rather than representative democracy by all Iraqi adult citizens, al-Mayah's public declaration directly opposed United States policy in Iraq.
Al-Mayah's bodyguard, Mohamed Sahib, did not have a gun since he was still waiting for a gun licence from US authorities. Sahib stated, They shouted for the car to stop... I remember one person fired directly at al-Mayah inside the car and I think another group also fired from the other side. He was shot three times in his head just as he was opening the car door to get out. He fell dead on to the ground.
Al-Mayah's brother told the New Statesman that his brother had received many emails advising him to be less outspoken in his criticism of the IGC. At least one came from an IGC member. Al-Mayah's brother stated, He never told me the name of this man, only that he was a dual national, someone who had come back from exile after the Americans invaded. He told me the man never actually threatened him. It was a sort of warning that it would be safer if he left the country. He was determined not to be swayed.
At Al-Mayah's funeral procession, a banner alleged that America and the Zionists were responsible for his death.
One of Al-Mayah's students, Salam Rais, supported the claim that a systematic campaign to kill Iraqi academics exists, stating His assassination is part of a plan in this country, targeting any intellectual in this country, any free voice.