Do caster level checks fail on a roll of a natural 1?

Question

All the SRD states is:

Caster Level Checks

To make a caster level check, roll 1d20 and add your caster level (in the relevant class). If the result equals or exceeds the DC (or the spell resistance, in the case of caster level checks made for spell resistance), the check succeeds.

So, does a 'natural 1' equal automatic failure? Or do you treat a 'natural 1' as just a roll result of one?

Answer 1

No

Critical successes and failures only apply when the rules say they do. Notably, you cannot crit on a skill check, caster level check, dispel check, or initiative roll, among other cases.

This is part of the level-based bounded accuracy of 3.x D&D, ensuring that characters cannot achieve results above their capabilities early merely by means of rolling a lot. For example, caster level checks are needed to Break Enchantment. For a sufficiently powerful mage (lets say a 10th level Cleric with Effective Caster Level 15), sufficiently weak effects (in this case CL 5 or lower) can be eliminated without rolling, while another band of effects (CL 6 to 24) require a roll and effects beyond that band are completely unbreakable from the standpoint of that Cleric (well... mostly. There are ways around that, of course, but this is 3.x D&D so there are ways around everything. This would be CL 25+ in our example). If, as the GM, I want to place an unbreakable curse on the Arch Lich's Tomb, I can make the curse CL 27 or so and know that my PC's Cleric wont be able to one-shot the plot device (with that specific spell). More importantly, a PC Cleric can't just plop a few dozen Break Enchantment castings into basically any magic effect in the world and be confident that it will break (now, they shouldn't be confident of that anyways, because there are tons of things specifically immune to Break Enchantment, but hey). Caster level thus becomes an effective determiner of a character's maximum capabilities with regards to effects dependent on Caster level checks, and GMs can plan accordingly.

Answer 2

What DarkWanderer wrote is correct, the rules for critical success or failures apply to where they are stated such as attack rolls in combat.

There has always been room in D&D for house rules and variations. In the DMG on p.239, the Automatic Success variation is discussed which is up to DM discretion, so long as the judgement is consistent and predictable. All D&D versions have given the DM some flexibility and their judgement to run a fun game (p.236 of the DMG, for example, which talks about using or ignoring the dice, or Inspiration a couple of pages from there).

You could play a House Rule that says 1 fizzles or fails. (http://forum.rpg.net/showthread.php?740888-5e-Your-house-rules is a thread discussing house rules and variations others have adopted in their own games.)

Since AD&D 1st ed, I have typically played 20 as success and 1 as failure no matter what, even for casting spells that require a die roll to hit (eg. Witch Bolt, PHB p.289 requires a ranged attack roll). A 1 is a critical failure, which allows some descriptive effects about fizzling or fumbling:

• "The air crackles with electricity then poof - the smell of sulfer and black soot surround the Wizard's surprised face as the spell fizzles!"
• "Before the last syllable rolls off Dramomere's tongue, he fumbles his components and drops them on the floor! The spell fizzles!'

Critical failures can be fun, everything from a character tripping and going prone to clubbing their party member or sticking a rapier through their own shoe, and use the opportunity for extra descriptiveness (likewise with critical hits).

However, these are all variations and not core 5e rules.