A petition challenging the appointment of Senate chairman Mohammedmian Soomro as Pakistan's caretaker Prime Minister was filed in the Supreme Court on Monday.
Petitioner Shahid Orakzai asked the court to declare Soomro's appointment as unconstitutional.
Soomro was appointed by President Pervez Musharraf as caretaker Prime Minister after the National Assembly and the government led by Prime Minister Shaukat Aziz was dissolved on the completion of a five-year term.
The petition filed under article 184(3) of the constitution asked "whether the Senate Chairman can be appointed as the caretaker Prime Minister".
Another question raised in the petition is "whether a person elected under the constitution and conducted an oath for an elected office can switch to any un-elected office without formally resigning his first office?"
Soomro did not quit as Senate Chairman before taking up his new post. It is expected he will resume his old post after guiding the country through the January 8 general election.
The petitioner asked the court to restrain Soomro from attending meetings of the caretaker cabinet or performing any other act under the constitution or any law till the petition is disposed of.