the police clearance certification

Dear friends,

"Workers whose sponsors refuse to issue them an exit permit, or if the sponsors are out of the country or have died, can seek a clearance certificate from a competent court certifying that they do not have a court ruling or a case against them and they would be allowed to travel out of the country without an exit permit"

This is from the newspaper.
I want to know what is "the clearance certificate"
where can i get it? from the which court? or from the police?