No Comma Before Conjunction When Clauses Share a Common Element
The Comma
Rulebase Summary
When there are two sets of subjects and verbs that share a common element after the second set, do not use a comma before the coordinate conjunction even though you have an independent subject and verb after it. The shared element (a direct object, noun clause, infinitive phrase, or other completer) serves both verbs, meaning the second clause is not truly independent.
Be on the lookout for this — once you are accustomed to always putting the comma for subject and verb after the conjunction, this exception is easy to miss.
Examples
A. He reviewed, and she approved the final report.
A. He reviewed and she approved the final report.
'The final report' is the shared object of both 'reviewed' and 'approved' — no comma.
A. The attorney asked, and the witness confirmed that the meeting took place on Friday.
A. The attorney asked and the witness confirmed that the meeting took place on Friday.
The noun clause 'that the meeting took place on Friday' serves both verbs — no comma.
Transcript Notes
This is another sophistication of punctuation that is easy to miss. The key is to identify when the element after the second verb is actually the object or completer for both verbs in the sentence.
Style Guide References (1)
BGGP