What happens if someone objects during the “speak now or forever hold your peace” part of a wedding?

Answer 1

It depends on the circumstances under which the party is objecting. For instance, if the objection comes from a disgruntled family member who simply disapproves of the union for personal reasons, then nothing would come of the objection—the officiant only asks for reasons "this couple cannot lawfully be joined." However, if someone were to object on the grounds that either the bride or groom were already married, for instance, or that one of the parties being wed was underaged, then the officiant would stop the ceremony and consider the claim.

Many modern wedding officiants omit the phrase entirely, since any legal red tape that might prevent the wedding would have been addressed when the couple obtained their marriage license, making the question more or less obsolete.