Society in general, and the courts in particular, have long been aware of explicit, discriminatory bias. Efforts to combat racism, sexism, classism, and homophobia in the justice system are ever-intensifying. And rightly so. Unfortunately, however, not all thinking errors are as well-known and recognisable as racism or sexism.

Our judgements are just as easily affected by biases that unconsciously seep into decision-making through seemingly irrelevant circumstance. These lesser known biases rarely make it outside of psychology journals into court procedure, but if you ever find yourself facing the justice system, the three questions below might become worryingly relevant.

1. Are you pretty?

What is beautiful is good. And judges, like most people, prefer the good-looking. In one study, police in Texas were asked to rate the physical attractiveness of over 1,500 defendants in misdemeanour cases. The researchers then followed the defendants through to trial, and found that the more attractive a defendant had been rated, the less likely he or she would be to receive a jail sentence or hefty fine. It pays to be pretty. In this case, literally.

2. Have the jurors washed their hands?

If you’ve done something that might invite headshakes, tuts, and murmurs of ‘disgusting’ (think assault), then this question might matter more than you think. We associate moral purity with physical cleanliness – the so-called ‘Macbeth effect’ – and how clean people feel can affect the harshness of their moral judgements.

In one study, people were asked to clean their hands with antiseptic wipes before rating how bad they found various moral transgressions. The squeaky-clean hand wipe group judged the transgressions more severely than their (comparatively) dirty counterparts.

Similar results have been found where people just see a hand-sanitizer dispenser, reminding them of cleanliness, or when participants are just told to visualise cleanliness.

3. (When) has the judge had breakfast?

If you want to bail before your trial and its ten minutes to lunch – bad luck. One recent study followed Israeli judges making parole decisions (deciding whether a defendant can go home to await trial, or must wait in prison). The judges would make between 4 and 35 of these decisions each day, and would have two food breaks diving the day into three sections.

Immediately after meal breaks, the judges granted approximately 65% of the parole applications. Immediately before meals breaks, when the judges were at their most tired and hungry, they granted approximately…0% of the applications.

The practical significance of these studies is still unclear. Some of the findings remain controversial, and no-one is advocating that trial judges snack throughout proceedings or that jurors be kept away from wash rooms (or should they?). What the studies do make clear, however, is that even tiny, unconscious errors in judgement can undermine the objectivity of the entire justice system.

If we are outraged at the thought of an innocent person being incarcerated on the basis of their gender or skin colour, how much more outraged should we be about someone being locked up because the jury found them unattractive, or because the judge was hungry?

The absurdity of the injustice is no less great, we just haven’t admitted that the biases that lead to racial discrimination also lead to less socially acknowledged, but no less devastating, mistakes.

Accordingly, the political will to stamp out explicit  bias in the justice system exists, but the will to extinguish lesser-known biases does not. Yet behind each flawed decision is a real individual deprived of their liberty or property.

While we live in a world where unconscious injustice is possible, the first step is to get it on the list enemies to be defeated. Only once we commit to real objectivity, can we  plan to achieve it.