Writs of prohibition can be subdivided into "alternative writs" and "peremptory writs". Defense attorneys exercised peremptory challenges against all seventeen potential black jurors. Generally, a plea could be dilatory or peremptory. Regard must be had to whether the provision imposing the duty is peremptory or permissive. Also, "jus cogens" (peremptory norm) is a custom, not a treaty. Flowers appealed to the Mississippi Supreme Court again arguing on the peremptory challenges. Refugee rights encompass both customary law, peremptory norms, and international legal instruments. Refugee law encompasses both customary law, peremptory norms, and international legal instruments. A peremptory plea had only one kind&colon; a plea in bar. There are often disagreements over whether a particular case violates a peremptory norm. Eight peremptory challenges are allowed for both counsels for all offences in Queensland. A treaty is null and void if it is in violation of a peremptory norm. The number of peremptory norms is considered limited but not exclusively catalogued. Peremptory challenges are permitted in Hong Kong. On May 31, McEnry finally told his followers to obey "peremptory orders" of the President.