A seven-judge bench headed by Justice Nasir-ul-Mulk issued a 77-page detailed order regarding the conviction of the premier for refusing to act on directives to revive cases of alleged money laundering against Pakistan President Asif Ali Zardari in Switzerland.
Earlier, the same bench had issued a short order when it convicted Gilani of contempt and gave him a symbolic sentence of less than a minute on April 26.
Even in the short order, the bench had hinted that Gilani faced possible disqualification.
The apex court referred to an earlier order it had issued on January 10, which had said that under provisions of Articles 63(1) and 113 of the Constitution, a conviction of contempt "may entail a disqualification from being elected or chosen as, and from being, a member of Majlis-e-Shoora (parliament) or a Provincial Assembly for at least a period of five years".
The seven-judge bench enumerated reasons for the conviction of the 56-year-old premier and analysed the evidence that was presented during his trial in the detailed order.
The detailed order said "the highest executive functionary of the state of Pakistan" had "wilfully, deliberately and persistently defied a clear direction of the highest court of the country".
Such "clear and persistent defiance at such a high level constitutes contempt which is substantially detrimental to the administration of justice" and brings the judiciary into ridicule, it said.
"After all, if orders or directions of the highest court of the country are defied by the highest executive of the country, then others in the country may also feel tempted to follow the example, leading to a collapse or paralysis of administration of justice, besides creating an atmosphere wherein the judicial authority and verdicts are laughed at and ridiculed," the detailed order said.
Former law minister Wasi Zafar told the media that Gilani's case would now go to the speaker of the National Assembly or lower house of parliament.
The speaker will decide whether the matter should be referred to the chief election commissioner, he said.
If the speaker decides to send the matter to the CEC, then the Election Commission will decide on the issue of disqualification, Zafar said.
Gilani, who on Tuesday embarked on a five-day official visit to Britain, has rejected demands from the opposition for his resignation after his conviction. He has said that only the speaker of the National Assembly can decide on his disqualification.
Under the existing rules, the speaker has 30 days to consider the issue of disqualification, following which the Election Commission has a further 90 days to decide the issue if it is referred to the panel.
The supreme court has been pressuring the government to revive the cases against Zardari since December 2009, when it struck down a graft amnesty issued by former military ruler Pervez Musharraf.
The government has refused to act, saying the president enjoys complete immunity in Pakistan and abroad.
The apex court's detailed order could exacerbate the ongoing standoff between the Pakistan People's Party-led government and the judiciary, which some commentators have accused of acting in an impartial manner against Zardari and Gilani.