
Islamic heresy: all Shi'ite countries have a CB on all Sunni countries, and vice versa. Embargo: a country has a CB on any country which has imposed a trade embargo on it. Ownership of Rome: if a country other than the Papal States owns Rome, all Catholic and Counterreform Catholic countries have a CB on it. War with the Papal States: all Catholic and Counterreform Catholic countries have a CB on all countries which are currently at war with the Papal States. Core province ownership: a country has a CB on any country which owns one or more of its core provinces. The following conditions create permanent CBs: There are many ways in which a country can get a casus belli on a second country. Note that "permament" is a bit of a misnomer, since some permanent CBs don't usually last very long. It ceases immediately if the condition causing it ceases. They are based on ongoing conditions in the game so long as those conditions are true, the casus belli will exist. Permanent CBs do not have an expiration date. (The exact day of expiration is not visible in-game you can see it in a save file.) You can see the date when they expire by mousing over them in the diplomacy screen, and getting a tooltip. All temporary CBs have a specific event in the game's history which caused them, and which their expiry date is related to. Temporary CBs all have an expiration date. There are two kinds of casus belli: permanent and temporary. In addition to the effects on DoWs, whenever a country has a CB on another, and it does not also have a royal marriage, relations between the two countries will decline slightly each month.
If it has no casus belli, it will take a larger hits to stability and badboy. The primary effect of a casus belli is seen only when a country declares war on another. Other countries it has a CB on will be shown in red, with "lightning" over their crown. You can see CBs graphically in diplomacy map mode by selecting a country. Temporary CBs are listed after the permanent ones. On the diplomacy screen is a listing of all diplomatic relationships a country has, including casus belli. There are several ways to determine the casus belli a country has in the game.