Legal translators are routinely faced with defective source texts in their professional practice while being expected to produce effective translations despite such quality issues. Given the high-quality expectations required in legal translation, we have brought this professional reality into the classroom by outlining a quality control activity to allow legal translation trainees to systematise how they deal with defective Spanish administrative source texts. The proposal includes two steps: a translatability assessment and a pre-editing stage of defective administrative source texts. After empirically testing our proposal in the classroom, our initial findings suggest that this approach not only assists trainees to factor in poor source text quality when translating, but also to produce better translations.