Wiktionary
vb. 1 (context legal English) To elicit information from a witness to show that the witness has knowledge of a matter before the witness testifies to the matter itself. 2 To make a start.
Usage examples of "lay a foundation".
I'd rather have one experienced person who understood the context - someone who might be able to help the two of us lay a foundation under the theory.
He might, perhaps, lay a foundation that would stand strong against the evil Storm was to bring.
Surely it is most obvious that regeneration must first take place in order to lay a foundation for our justification.
The process helps to lay a foundation for a positive relationship between the generations and opens doors to future confidences and dialogues as the grandchild matures.
He will pick up a vote or two and lay a foundation for the final campaign.
You'll have to lay a foundation for that and get it in by proper evidence later.