The article engages with the old debate about the diachronic relationship between Leviticus 11 and Deuteronomy 14. It starts with outlining certain criteria which might help us determine directionality. It then provides a synchronic overview of the two chapters, focusing on commonalities and differences, before moving on to the diachronic debate. As part of the diachronic debate the views of Christophe Nihan and Reinhard Achenbach are contrasted and critiqued. The article then attempts to draw some conclusions from this debate.