I was curious so found
this report giving more detail about the study. Has some interesting stuff.
"Complexity" isn't necessarily a "well, duh?" answer. Other things that came immediately to mind as possibly producing more hung juries were:
1. Number of charges. IF the indictment has 43 charges to consider, even if each is straightforward, do juries just kind of give up.
2. Duration of trial (the report I see does mention that and found that juries did not necessarily view long trials as more complex).
3. Power relationship of the parties (a friend was on a jury that hung after mroe than a year of trial and deliberations because one juror essentially said "I can't find a cop guilty.")
4. Perception of competence of the lawyers/judges.
5. Issues likely to produce nullification attempts by at least one juror ("I know technically he's guilty, but I don't like the law")
6. Social dynamics among jurors in deliberations. Interestingly (to me it seems counterintuitive) juries that hang take their first vote earlier in deliberations than juries that don't hang.