Three Afghan refugees are taking legal action against the Home Office claiming conditions at an immigration centre near Gatwick were unlawful.
The three men who were detained at the then G4S-run Brook House, say detainees were locked up for 11 hours overnight.
The High Court heard the regime broke their right to liberty and privacy.
They claim the regime subjected them to “a discriminatory and/or disproportionate interference” with practising Muslims’ right to religious freedom as they had to pray in their cells
Mr Justice Cavanagh, who will hear the case over three days, is expected to reserve his judgment.