Ernst has made a number of research contributions to the emergent field of deaf studies through projects in sociology, linguistics and education. He variously held positions as senior research fellow or senior lecturer at the Universities of Durham, Central Lancashire and Edinburgh. Projects have included research commissioned by the UK Department for Education and Employment (DfEE) and the Scottish Executive Education Department (SEED).
Ernst is also a typographic designer, designing lexicographic products, academic publications and sign language notation systems.
Currently his research focuses on social differentiation and 'new' research practices. Projects have included the professionalisation of sign language interpreters and systems used for tracking deaf pupil achievements. VKS projects include a project on e-philology, an account of interventionism in science and technology studies and a study of corpus sign linguistics.