FA von Hayek was one of the great classical Liberals. He wrote about emergency powers in The Constitution of Liberty and approved of the practice.
For Hayek, laws in a free society are nothing more than rule of thumb. In an emergency they must be suspended for the sake of long-term order. Even freedom of speech can be suppressed under the ‘correct’ circumstances.
To preserve his libertarian ideal, Hayek attaches provisions to the state of emergency. Indemnity is proposed for those private individuals affected by the emergency. Such ex post facto judgements have happened in countries like the UK and pose no problem as such to the operation of a state of emergency.
Hayek’s other proposal is more fanciful. He wants the state of emergency to be ruled upon by a court.
Now, in a real emergency a court can’t deliberate for any meaningful period of time. However, if a court merely rubberstamps an emergency without fully assessing the facts, then it is not a court. The very point about emergencies, which Hayek loses, is that they are indefinable and by the time the court could make a reasonable judgement the emergency would have progressed too far.