Do you also make people who attack choose which critical feat to apply BEFORE the first attack roll? No, the rules are to choose when you critical.
While the rules are silent on whether or not you can choose to fail a check they are not silent on when you get to choose things. All sorts of effects pertaining to an attack roll are chosen after the fact.
There is a precedent for you to be able to choose to do things between the attack that is a critical threat and the confirmation of that critical threat.
Anyhow, <in Stark's voice> my game your game. :)
Wraithstrike: Before the crit attack is rolled. The crit attack roll is a separate attack roll.
Attack roll 1 (normal attack): Roll to hit. Assume critical threat.
Attack roll 2 (critical confirmation):
Player states he does not want to critical.
GM says 'no, you cannot do that, it is not in the rules'.
GM says 'ok, you fail your critical attack roll, roll the hit's damage normally'.
I guess it depends on whether you look at it as if we roll to determine the action or we roll to find the result of the action, with saves being the exception.
The combat chapter says it is to find out which is how I have always viewed it anyway.
Critical Hits: When you make an attack roll and get a natural 20 (the d20 shows 20), you hit regardless of your target's Armor Class, and you have scored a “threat,” meaning the hit might be a critical hit (or “crit”). To find out if it's a critical hit, you immediately make an attempt to “confirm” the critical hit.
Of course that could be read as "to make sure it is a critical hit..." so both views have merit.
In any event that is why using the other end of the weapon as a improvised weapon or attacking non-lethally are better for you. It reduces the chance for a crit or lethal damage. I am starting to think the player in question is not really trying to take any prisoners, unless he crits on the last attack. He could however use a backup weapon, or if he scores a crit up front he could let the rest of the party take the enemy down.
Back to the OP's situation
When it comes down to it there are ways to stop this from happening if the player really wants to stop it that avoid any houserules being needed.
PC:Oops I killed him again
PC2:Stop using the sharp pointy end of your weapon.
That is not a guarantee, just like getting iron will does not mean you will make a will save, but it does help.
Again, my point is that it in RL it is possible to avoid making a critical (contrary to some people's opinions). How that translates into PF is another matter. Currently, it does not translate. It is not part of PF rules to choose to fail a D20. However, this thread has gone well past the rules into 'you cannot do it in RL, yes you can, no you cant...'
And my point is that, in real life, you see you're about to strike your opponent in the neck, redirect your swing, and end up striking your opponent in the neck anyway because your opponent moved in an attempt to avoid your swing, because s/he didn't know you were going to adjust your swing or how you would do so if you did.
I don't disagree that people can change how they throw a swing, even mid-swing. My point is that accidents happen. You can't control everything. When I broke the other guy's rib, it wasn't because I was being careless; I actually pulled the kick. He lunged in, trying to counter the technique he thought I was throwing, much farther than I anticipated, resulting in my pulled kick still penetrating farther than I intended on a particularly vulnerable spot of his body (floating rib).
So, to put it in game terms, despite not using my full strength bonus to lessen the extent of the blow, I still rolled a 20 and confirmed the threat.
I am firmly in the camp of, "If you want to do something funky, you need to tell me BEFORE any dice roll."
So yes, I would absolutely allow a fighter to say, "I want to attack normally, but I don't want to crit." If I were feeling particularly ornery, I'd say that was akin to doing nonlethal damage and I'd throw in a -2 attack modifier. I am very generous with players who tell me what they're planning on doing ahead of time. Drop their STR modifier? Fine. Use their first 2 attacks, pause to see whether the enemy has fallen, and then follow through with their third attack only if the enemy is still standing? Fine. But once that die rolls, you're doing whatever you normally do, period.
For example, if the rest of the party said, "Don't kill him! We need him for questioning!" and the fighter said nothing and rolled a 20, I'd say, "Oops! You didn't hold up in time. Go ahead and roll that crit for me!" If he didn't tell me he was holding back before he rolled, he's not holding back.
But as I've said, I'm an old-school 'statement of intent' kind of guy. It takes very little time, and it avoids all kinds of arguments like this one.
Straight answer: no.
A critical threat commands a confirmation roll.
Anyone using anything can take a penalty and attempt to deliver nonlethal damage, if that is their honest intent... but it must be made clear before the attack roll is made.
There are feats and traits designed to mitigate the penalty for using a lethal weapon to inflict nonlethal damage, but the confirm critical rules are pretty set in stone.
When striking with the flat of the blade for Subdual as we used to call it In theory the sword should revert back to only threatening on a 20. Where in the increase was from the sharp part of the blade that you’re not using at the moment?
Old thread much?
Attacking with a falchion nonlethally doesn't involve striking "with the flat of the blade". It's still slashing damage. It doesn't change the critical range or modifier.
Because my table uses the crit and fumble cards we use this system. When you confirm a critical your handed a card face down. If you look at it you use it. If you keep it face down you can hand it back to the GM face down to negate a fumble.
With modifers its 1 card for X2, 2 cards for X3 and 3 cards x4.
Our table has agreed the fumbles are way more balanced then a GM just picking a what happens cause you rolled a 1 and the crit cards add a lot of flavor.
As others have said, the attack roll is integral, rolling for crit isn't separate from rolling to hit. One cannot use a reroll to reroll only the crit confirmation for example - unless specifically mentionned - as a reroll would have the whole attack roll rerolled.
A comparison can be made with systems that have dice that explode on the highest value, either d6 for Shadowrun or d10 for 7th Sea or L5R, one cannot choose not to have a die explode.
Any deviation from the standard attack aiming to deal maximal damage has to be announced before rolling.