I've a DWI case where the pull-over deputy was later named as a witness in a civil discrimination suit filed against the county sheriff office.

The civil suit was non-suited by the plaintiff.

The plaintiff worked under the deputy, now a captain.

Is this disclosed? Allegations with no findings?

the judge is trying to decide whether he is going to allow the defense to go into questions about this matter with the witness.

Will this open the floodgates in requiring disclosure of every single time somebody files a complaint against an officer, regardless of the findings, that there will be a burden to disclose.

I'm confused. Two questions:

(1) If the defense already has the information, then what's the Brady/Morton/Schultz problem? It's already been disclosed, right?

(2) If the deputy was a witness, and not the alleged "discriminator," how is that exonerating/impeaching/mitigating to this defendant?

I agree with both things you are asking.
To answer your questions:

1) defense wants to re-open a motion to suppress and force the Sheriff dept. to disclose the Captain's personell file and everything related to this civil case.

2) The Captain was not a named party, but was alleged as the main antagonist of the discriminatory behavior.

I was hoping there was a case on point about civil suits, allegations, and disclosure, particularly where the allegations were later dropped or found to be not true.

The hearing is concluded and the judge is going to perform an in-camera inspection of way more things then a reasonable defense would need for a DWI. Basically he's trying a smear campaign instead of a DWI trial. Real nice guy.

I think the short answer is that, yes, you need to at least have a judge do an in-camera inspection of these facts in every case that involves this officer. At least for now, that's your only safe bet. If you do anything else you're running a risk.

The real question is "does any of this info ever come in?" and THAT answer is much more clear: no.

There's a myth in the defense community that prior "bad acts" such as these can somehow be used both as propensity evidence or evidence of character for truthfulness, and that they are somehow excepted from hearsay.

But you can never use extraneous acts to prove conformity, you can only impeach for truthfulness with opinion evidence, and unless your officer says something in your criminal case that is inconsistent with a prior statement under oath, it's all hearsay anyway.

I believe you are right, especially when all the court has is civil allegations that were later non-suited.

At the very least, it should be inadmissible at trial. I'd just like a ruling that it is non-discoverable to keep other attorneys from trying to jump down this rabbit hole.