Does a summoned monster's alignment matter?

Question

I am playing in a 3.5 game recently, and a question has come up that none of us could really answer. Does the alignment of a summoned monster (as per the Summon Monster I-IX spells) matter at all? For example, if a Neutral Good Elf Wizard casts Summon Monster V, and pulls out a Fiendish Deinonychus, does the monster then disobey, being Lawful Evil? Or does the creature follow the whim of its summoner, regardless of alignment?

Answer 1

A summoned monster's alignment only matters if you're a cleric.

The summon monster spells are of the same alignment as the creature you summon (e.g. summoning a Dretch is a Chaotic and Evil spell). A cleric is forbidden from casting spells of alignment opposed to his alignment or his deity's alignment.

A good-aligned wizard can freely summon fiendish creatures. There is no penalty for a good-aligned arcane spellcaster using an Evil spell. It may affect his reputation in society, but there's no mechanical penalty. Creatures summoned with summon monster spells obey the caster regardless of alignment, provided you can speak their language (and if not, they automatically attack your enemies).

Answer 2

Summoned monsters' alignments can also matter if you're putting them up against an enemy with protection from, magic circle against, or dispel chaos/evil/good/law and related spells.

Answer 3

The creature follows the whim of its summoner, provided it can be communicated with, or just attacks the summoner's enemies to the best of its ability. As already noted, its alignment sets the alignment descriptor of the spell (which DOES matter for clerics) and matters while interacting with alignment-based spells. Please note that the summoned creature is extraplanar, which may also matter.