Charles Ellicott Commentary Romans 5:21

"that, as sin reigned in death, even so might grace reign through righteousness unto eternal life through Jesus Christ our Lord." — Romans 5:21 (ASV)

Unto death.—Rather, in death; death being, as it were, the domain in which its sovereignty was exercised.

In this last section we seem still to trace the influence of the school of Gamaliel. It appears that the Jewish doctors also attributed universal mortality to the fall of Adam, and regarded his sin as including that of the rest of mankind. (On the whole section, see Excursus F: On St. Paul’s View of the Religious History of Mankind.)