Does a children's aid society worker's opinion carry the same weight as expert evidence in family court?

Not automatically. A children's aid society worker can give evidence about what they observed, what was reported, and what steps the society took - that's factual, first-hand evidence and can be valuable to a family court judge. But a worker's personal opinion about deeper questions, like a parent's underlying psychological fitness or long-term risk, isn't automatically treated the same way as evidence from a qualified expert, such as a psychologist, who has been formally qualified by the court to give opinion evidence on a specific subject.

In practice, a judge will weigh a worker's evidence based on their direct involvement, their training, and how their observations are documented, but a party who wants a more clinical assessment - for example, of parenting capacity or risk of future harm - typically needs to arrange for a proper expert assessment, sometimes through a court-ordered process, rather than relying on the worker's opinion alone to carry that weight. If a worker's evidence is being relied on heavily in your case, ask your lawyer whether an independent expert assessment would strengthen or test that evidence, since the two serve different roles in a family court proceeding.