Members of the United Purple Nations are not allowed to raid any nation residing in an alliance with 10 members or more.
Nor can they raid members of an alliance with an active Protectorate or Defense treaty.
UPN members shall not raid any nation who has been active within the last 24 hours or who's residing on the Purple Colour sphere.
In addition, all raiders must acknowledge that they are responsible for their own actions and that the alliance is not obligated to assist them should their raid prove disastrous.
This can be found in the UPN Charter - The Purple Documents
, Section I. Admission Failure to Abide by these Rules
Any member who breaks the raiding policy shall be kicked from UPN upon multiple offences or if they disobey orders to cease their raiding activities. Each incident will be reviewed by the UPN Council.