45b. Titles with proper names

45bCapitalize titles of persons when used as part of a proper name but usually not when used alone.

Professor Margaret Barnes; Dr. Sinyee Sein; John Scott Williams Jr.

District Attorney Marshall was reprimanded for badgering the witness.

The district attorney was elected for a two-year term.

Usage varies when the title of an important public figure is used alone: The president [or President] vetoed the bill.