What is "exceptional case-marking"

n. (context linguistics English) A phenomenon where the the subject of an embedded infinitival verb seems to appear in the superordinate clause, and if a pronoun is unexpectedly marked with object case morphology.

In linguistics, the term exceptional case-marking (ECM) denotes a phenomenon where the subject of an embedded infinitival verb seems to appear in the superordinate clause and, if it is a pronoun, is unexpectedly marked with object case morphology (him not he, her not she, etc.). The unexpected object case morphology is deemed "exceptional". The term ECM itself was coined in the Government and Binding grammar framework, although the phenomenon is closely related to the accusativus cum infinitivo constructions of Latin. ECM-constructions are also studied within the context of raising. The verbs that license ECM are known as raising-to-object verbs. Many languages lack ECM-predicates, and even in English, the number of ECM-verbs is small. The structural analysis of ECM-constructions varies in part according to whether one pursues a relatively flat structure or a more layered one.