viretarmis:

"only to the people who broke the law."

So floating will tell us guilt and drowning will tell us innocence? Most felony cases never go to trial and are plea bargained. One reason for this to happen. The state or fed doesn't care to prosecute, offers a plea, and hopes to cut the trial time by ~ 2/3rds. God-forbid they have to work and take a case to trial. 80-90% of all cases end up this way

People who lack monetary resource or a good attorney find themselves accepting the plea bargain rather than fight the charges. In any case, the witch is never put to the test and neither is the test proven to be an exemplary prover of guilt as the percentages of guilty but innocent are higher than they should be.