One of the simplest writing mistakes is misusing commas with names followed by a title or degree. The rules are simple, but can be confusing since they vary based on the type of term, the context and sometimes even the preference of the name holder.
Commas for Degrees
Use a comma between the name and the abbreviated degree, as in "Joe Smith, M.D." This also applies to professional titles; for example, "Mary Richards, director of development." If written in a sentence, include a second comma after the degree or title: "Joe Smith, M.D., will speak at the conference." Do not include the second comma if the name ends the sentence: "I plan on having lunch with Joe Smith, M.D."
If a person's name has Junior (Jr.), Senior (Sr.), II or another like term, it is not necessary to include any commas; for example, "Joe Smith Jr. is a very generous person." However, some people may follow older conventions and choose to write their name using commas: "Joe Smith, Jr." If you know this to be the case, it is appropriate to also write the name this way. In a sentence, set it off with commas the same way you would with a degree title: "We will know what Joe Smith, Sr., has decided any minute now."
When titles and degrees are used in the possessive form, do not include the second comma: "Joe Smith, M.D.'s speech was very moving."
Titles Before Name
Do not use a comma for titles that appear before the person's name, such as "the Reverend Joe Smith" or "Doctor Mary Richards." Also do not include both a person's title, such as doctor, and their corresponding degree, such as M.D., at the same time.