i dont think it is easy for courts/judges - though there is research etc to assist in making assessment eg www.lundybancroft.com/?page_id=261
but if there has been little documened violence/abuse it can be hard to make that judgement - some separations the parties are angry/bitter but no one kills anyone.
maybe mandatory counselling/therapy for all splits?
courts dont have time/money for full forensic psychiatric evaluations and in eg cases where parent is upstanding GP etc then unless he screaming in the court judge is likely to order unsupervised contact...and even if supervised at a contact centre, if this goes well, there will be unsupervised eventually. someone could play the long game while planning ultimately to do something the day they get the kids alone.. .
consensus seems to be with the men it is about anger/bitterness...(if women it is about depression) how do you treat that? unless there is previous serious criminal violence then only the person themselves can seek help for that anger... (or depression).
if they dont see their anger or their plans as an issue and dont express that so that someone can act - then how can you possibly get into someone's head and decide this is what they planning?
however, tehre should be awareness and judges should maybe take concerns expressed by people asking for supervised contact more seriously ... look for the flags... like anger etc. not be taken in by the "perfect dad" scenario.
it is awful when it happens ...