The Peshawar High Court (PHC) on Thursday declared the orders of the arrests passed under Section 3 of the Maintenance of Public Order (MPO) "null and void".
The court nullified the orders issued by deputy commissioners while announcing the reserved verdict over the pleas against the arrests under MPO.
A detailed written verdict will be issued later.
The district administrations across Khyber Pakhtunkhwa (KP) had enforced Section 3 of the MPO and made hundreds of arrests in the wake of violent protests triggered by Pakistan Tehreek-e-Insaf (PTI) Chairman Imran Khan's arrest.
Police had arrested over 1400 people, mostly workers of the PTI, for their alleged involvement in violent attacks on police and army installations, public and private buildings, checkposts, ambulances and other vehicles during the rallies taken out by the party to protest Khan's arrest.Several people among them were arrested under the MPO.
A total of seven people had lost their lives while over 106 civilians and 36 policemen were wounded in clashes alone in Peshawar and other districts of KP during two days of violent protests by the PTI workers.
Earlier, the PHC had ordered the release of PTI workers held under MPO on May 19.
The high court suspended the detention orders issued by deputy commissioners of different districts in KP.