A decision on whether to prosecute Cadbury for breaching food safety laws in relation to salmonella contamination of its chocolate products earlier this year could be months away.
Darren Smith, a partner in law firm Reed Smith's product liability practice group, said: "The big risk will be that if legal action is unsuccessful, Cadbury could ask the councils to pay costs, which could be huge."
He added: "Birmingham [City Council] and Herefordshire [Council] will be conducting interviews with employees at Cadbury under caution before taking their evidence to a barrister or QC to assess the merits of the case. In an action as high-profile as this, you can't afford to make mistakes."
A defence based on a claim that Cadbury acted in good faith when it failed to inform the authorities of the contamination in January, because it believed there was no risk, was not compelling, he added. "Ignorance is no defence. It is incumbent on a company this size to keep abreast of developments in risk assessment."
The EU General Food Law also stipulated that if there were any "scientific uncertainty" in such an incident, the precautionary principle should apply, in which case a recall should have been issued anyway, he added. Unless every expert consulted by Cadbury was convinced there was no food safety risk, this also suggested it was potentially in breach of the law by failing to act earlier.
Herefordshire said: "We're working with Birmingham, but there are several possible offences being investigated, some general, others about plant and premises."
The outbreak, at Cadbury's factory in Marlbrook, Herefordshire, is expected to cost the company £26M, of which just £6M will be covered by insurance. Half of the total related to the recall and the balance to one-off manufacturing improvement costs and increased media costs.