You can also simplify.

• calculate the ratio of convicted (or indicted) per civilian casualties for each war / ethnic group
  
• do a test to identify whether the differences between the means of these ratios is statistically significant from one group to another.
  

If it is, you probably have a biased court. If it's not, you probably don't have a biased court.
I used the t test because its appropriate for small data samples in a normal (Gaussian) distribution, which is an assumption that seems ok to me.