Semicolon sometiems acts as a "supercomma".
e.g.
Science fiction sagas with the most memorable characterization are Star Trek, with Mr. Spock and his large pointed ears; Aliens, with the ever-harassed but always-capable Lt. Ripley; and Star Wars, with Han Solo, Luke Skywalker, and Darth Vader.
Example from http://home.cerrocoso.edu/marvin/handouts/comma4.htm
If there is at least one internal comma within each item, a semi-colon will be used to separate between A, B, and C. (like a, a, a; b, b, b; c, c, c)