So you've got me scratching my head now as to why, in response to my previous post, you would seek clarity by submitting a follow-up question that yet again fails to even mention passive checks.
The only answer I can come up with is that it's a deliberate evasion. I hope that this is not the case, but it's hard to see another explanation..
For shame. Sometimes what seems very important to one, and indeed, what one has stressed repeatedly, seems unimportant to another such that they neglect it.
On my part, I really scratched my head over your dismissal of
always.
I don't consider CSR to have a particularly useful record as arbiters of rules interpretation,
True, but they are a neutral and informed third opinion. I view asking them as like getting a ruling from an RPGA DM. WotC would support that ruling on the day, but it's still only one DMs ruling based on what they know. It's like trial precedent, I suppose. Informs, but doesn't necessarily determine legislature.
Background:
The rules for opposed skill checks (PHB 178) say that both parties roll checks.
The rules for passive checks (PHB 179) say that they are a form of opposed check in which only the active participant rolls, the passive participant using a fixed skill value as though they had taken 10, and that they're used whenever a character is not 'actively' using a skill.
I put actively in quotes because I'm not sure whether it means 'intentionally' or 'consciously', or whether it carries the same mechanical meaning as 'active'.
Both sections use Stealth vs. Perception as an illustrative example, with the passive checks section specifying a situation in which those making the Perception checks aren't actively looking around for danger, and opposed checks specifying a situation where a character is hiding while another tries to see them.
The Stealth skill description (PHB 188) describes Stealth as an opposed check, Stealth vs. Perception, and usually this check is taken in one character's turn at the moment they try to perform an action stealthily.
The Perception skill description (PHB 186) states that the DM usually uses your passive Perception check, and that you need to take a standard action to use the skill actively.
Question:
When making an opposed Stealth vs. Perception check during combat, do those opposing the Stealth check use their passive Perception, or roll Perception checks? Or is it up to the DM based on what the players have described their characters as doing? For example, would characters who say they are alert to danger make 'active' checks even though it's not their turn, while characters who aren't looking out for danger would make passive checks?
If the latter, does this require any action on their turn? Related to that, is an active check only a check you can make using an action on your own turn, or does 'active' just mean 'you roll the dice' and you can make an active check in someone else's turn if you have to?
Heh - lots of leaning all ways. But... okay?
BTW There's been a CSR on which result you use: you use the higher result. Actually it might bear on this... if only I could locate the question! Here's the answer
'The DM can choose to use either active or passive perception checks to notice Stealth. Even if an active check fails, if passive would succeed the check succeeds. An active roll is just a chance to roll better.'
-vk