In our world, the police going to a spirit medium for the DL-6 case, and being ridiculed might be logical, since spirit channelling isn’t a real thing, but in the world of Ace Attorney, it is.

Not only is it a known and established practice, with detectable physical effects, but the monarchy of at least one country is specifically sought out for their spirit-channelling powers by other governments, so that they can commune with the dead, and receive advice that way.

However, it also seems to be disbelieved, and ridiculed as a pseudoscience, despite that.