the irony of salem witchcraft trials it that they were meant to preserve order, promote morality and serve justice instead they have the opposite effect... critically analyse this

The people of Salem pretty much do the opposite of your statement. The irony is that these Puritans escaped intolerance and oppression of their beliefs in England and only to build an even more rigid and controlled society. On the surface Salem might come across as pious and orthodox but underneath, their society is a toxic mess of hypocrisy and vindictiveness. Neighbours use orthodoxy settle old scores with other neighbours. The village priest (Paris) is only concerned with his "reputation" and money. The only justice the witch court sees is perpetuating their own existence by finding innocent people to be witches whatever town they happened to be called to.