§ 2030.310.Amended answers to interrogatories; use at trial; motion for order binding

Answers to interrogatories are not frozen the moment they are served. This section lets a party serve an amended answer, without needing court permission first, whenever the amendment reflects information discovered afterward, information left out by accident, or a mistake in how the original answer was stated. That flexibility is not unconditional at trial, though: subdivision (a) preserves the propounding party's right to use the original answer under Section 2030.410 even after an amendment, with the responding party then free to introduce the amended version as well, letting the fact-finder weigh both the original statement and the correction.

Subdivisions (b) through (d) address the situation where an amendment shows up too conveniently, changing course only after the original answer has already caused real damage to the other side's case. The party who propounded the original interrogatory can move, backed by a meet-and-confer declaration, to have that initial answer deemed binding on the responding party for the rest of the case. The court has to grant that motion if three things are all true: the initial wrong answer substantially prejudiced the propounding party, the responding party cannot show substantial justification for having given that initial answer, and the prejudice cannot be fixed either by a trial continuance to allow more discovery or by using the initial answer against the responding party at trial on its own. As with other motions in this chapter, subdivision (d) requires a mandatory sanction against whichever side loses this particular motion, absent substantial justification or unjust circumstances.