Is the integrated/non-integrated distinction for embryo models really obsolete?

Stem cell-based embryo models (SCBEMs) offer new ways for studying early human development while circumventing ethical challenges associated with natural embryos. Traditionally, SCBEMs are categorised as ‘integrated’ or ‘non-integrated’, reflecting their capacity for coordinated development and potential to acquire morally relevant properties. However, the Code of Practice challenges this distinction, arguing that non-integrated SCBEMs can reach stages of significant developmental complexity, making the classification obsolete. This paper critiques the abandonment of the integrated/non-integrated framework. I argue that the distinction is tied, rightfully so, to developmental potential rather than structural complexity. For the ethical oversight of embryo models, the potential to develop morally relevant properties and thus the integrated/non-integrated distinction remains relevant.