[gospelwut]

As somebody that often gets hired to say things in a legal setting, I will confirm you can (unfortunately) find an expert to say anything (to a point). This is generally why the option for a neutral party is available (but expensive).

No idea if Congress has that option.

[rsingel]

Yes, they have the valuable Congressional Research Service to do non-partisan evaluations. Their reports are great, though often not made public.

[gospelwut]

I'm curious why they wouldn't make it public. I'm sure 95% of people wouldn't read them.

[cbs]

If they're public, congress members have (even more) incentive to influence them to publish bullshit that fits their ideology rather than facts and/or accuse them of bias towards the other party.