In his ruling judgement at the weekend, Justice Kapanda said a judicial review on the legality of the appointment should be conducted within a fortnight.
Mpasu has declined the appointment because he fears it is a way of "neutralising him" politically. The beleaguered Speaker told PANA Monday his appointment is suspicious because he was never consulted.
"I see it as an indirect move to dismiss me ... I will be wrong to accept the job because it puts the legislature in an awkward situation," he said.
Before Justice Kapanda's ruling, Mpasu's lawyer Ralph Kasambara had argued that Section 53 of Malawi's constitution says that one ceases to be Speaker of Parliament when one becomes President, Vice President or Minister.
However, the Section 95 of the same constitution says one becomes a minister after taking an oath of office and allegiance.
"My Lord, Honourable Mpasu has refused to accept the post of Minister of Commerce and Industry so he is still Speaker of the National Assembly (Parliament)," he said.
President Muluzi fired two senior ministers who disagreed with his selection of an economist Bingu wa Mutharika as his successor when his terms of office ends in 2004.
Most senior officials of the ruling United Democratic Front (UDF) see the former COMESA executive secretary as a complete outsider.
Among these was the former UDF First Vice President and Agriculture minister Aleke Banda who quit the ruling party last Friday over the succession wrangle.
Mpasu, who also expressed interest in the presidency, could not be fired since the president has no constitutional powers to fire a sitting Speaker of Parliament.
He claimed that Muluzi has decided to appoint him to his cabinet where he as absolute prerogative to hire and fire.
As to whether he might not automatically lose his job as Speaker after openly defying the president's decision, Mpasu said nobody appointed him to that he was elected by MPs.
"The Constitution is clear how a Speaker of Parliament can be elected or removed," he said.
However, in another interview, Malawi's Attorney General Peter Fachi said since the president appointed Mpasu to his cabinet it was automatic there is a vacancy at the Office of Speaker.
He said if Mpasu continues his defiance, the government will withdraw all trappings of the Speaker because "he is now minister and automatically the office of the Speaker is therefore vacant," he said.
Edge Kanyongolo, who heads of the Law Faculty at Chancellor College of the University of Malawi, said although Muluzi has the prerogative to appoint anyone to his cabinet, the appointee has the right to accept or reject the appointment.
Until Mpasu takes the oath of office as Minister of Commerce and Industry or he is impeached from Parliament, he is legally still Speaker, he argued.
"If Hon. Mpasu has refused to take up the cabinet post then he will remain Speaker and there is no offence because a person appointed to cabinet is free to accept or refuse," the lawyer said.
All this makes for a very fluid political scenario as Malawi edges closer to the scheduled 18 May 2004 general elections.
Analysts say President Muluzi is bitter with senior UDF officials because they frustrated his bid to stay in office after his constitutionally allowed two five-year terms of office expire next year.