High Court Judge Chacha Mwita ruled that, under Kenyan law, the authorities could only deploy officers abroad if a "reciprocal arrangement" was in place with the host government.
"Any further action or steps taken by any state organ or state officer in furtherance of such a decision, contravenes the constitution and the law and is therefore unconstitutional, illegal and invalid," Mwita said.
The Kenyan government had offerred to lead a mission to Haiti but it has been ruled unconstitutional.