If you are cross-examining a witness, don’t comment on his answers.
That needs a little explanation. You can ask follow-up questions of the sort “But that makes no sense, does it, because…?” You can contradict: “But if you turn to page 247 of the bundle, we can see that that can’t be true?” You might even want to summarise the last few answers for impact: “So you’d seen Chris crying at her desk more than once in the last week, you knew she’d recently been off with stress, you were aware her GP was asking for her to be given a less pressured role, you’d read the OH report, you knew the Productions Team was under exceptional pressure, you knew the team leader had the reputation of a bully – and knowing all that you thought transferring her to Productions in the final month before the launch was reasonable?”
In a sense those sorts of questions are comments, but they are comments of the kind that call for an answer, and so a legitimate part of cross-examination. The point is to put the witness on the spot.
But comments like “We don’t agree with that,” or “We’ll have to agree to differ there,” or “That’s just not true!” don’t put the witness on the spot at all – you’ll either get a shrug in response, or a bit of panto of the “oh yes it is!” – “oh no it’s not!” variety. Neither takes the case any further forward.