(103)Tenders that appear abnormally low in relation to the works, supplies or services might be based on technically, economically or legally unsound assumptions or practices. Where the tenderer cannot provide a sufficient explanation, the contracting authority should be entitled to reject the tender. Rejection should be mandatory in cases where the contracting authority has established that the abnormally low price or costs proposed results from non-compliance with mandatory Union law or national law compatible with it in the fields of social, labour or environmental law or international labour law provisions.