His views became known more widely in November when he sought pardon for a Christian woman given the death penalty after being accused of criticizing the Prophet Mohammed. Pakistan's blasphemy law provides for a death sentence for anyone found speaking against Islam, the Koran or the prophet.
In a November CNN interview about Asia Bibi, 45, who was condemned to death, Taseer said he expected Pakistani President Asif Ali Zardari, whom he described as "liberal, modern-minded," to pardon the woman even if the court did not.
"The blasphemy law is not a God-made law," Taseer told CNN. "It's a man-made law ... .It's a law that gives an excuse to extremists and reactionaries to target weak people and minorities."
Taseer also had spoken out in support of women and minorities in Pakistan.
Pakistani police and authorities say he was shot and killed by his own security guard who later surrendered.
Pakistani Minorities Minister Shahbaz Bhatti told CNN he would continue with Taseer's campaign.
"I will campaign for this ... these fanatics cannot stop me from moving any further steps against the misuse of (the) blasphemy law," he said.
The BBC quoted Pakistani Ambassador to England Wajid Shamshul Hassan as saying Taseer's assassination exposed the divisions in his country.
"It has shown that you can be held hostage by a minority of (radical) religious people and they can do whatever they want. That is not the way we are going to allow in the country," he said.