class CampaignPolicy < ApplicationPolicy
  def destroy?
    user == record.game_master
  end

  def update?
    destroy?
  end

  def create?
    record.member?(user)
  end

  def toggle_membership?
    user.present?
  end

  def new?
    record.member?(user)
  end
end

class CampaignPolicy < ApplicationPolicy
  def destroy?
    user == record.game_master
  end

  def update?
    destroy?
  end

  def create?
    record.member?(user)
  end

  def toggle_membership?
    user.present?
  end
end

--- 
+++ 
@@ -14,4 +14,8 @@
   def toggle_membership?
     user.present?
   end
+
+  def new?
+    record.member?(user)
+  end
 end
Add policy for new campaign
