back-and-forth

The quotation comes from With a Picked Lock and a Threatened Indictment, Mueller’s Inquiry Sets a Tone

Quotation: Some lawyers defending people who have been caught up in Mr. Mueller’s investigation privately complain that the special counsel’s team is unwilling to engage in the usual back-and-forth that precedes — or substitutes for — grand jury testimony. They argue that the team’s more aggressive tactics might end up being counterproductive, especially if some grand jury witnesses turn out to be more guarded than they would have been in a more informal setting or invoke the Fifth Amendment.
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Hi everyone! How should I understand “back-and-forth” in the context?

It is referring to an exchange of information - essentially "informal discussions" in this context.

I see "back-and-forth"(n.) as a metaphor that uses the game of tennis in which the ball goes back and forth (adv.) across the net in the hopes of defeating the opponent. In this case, the lawyers are trying to defeat each other (probably by making arguments and objections and requests on procedural matters) prior to the actual hearing.