Beyond reasonable doubt: the use of experts in Environmental Protection Act 1990 prosecutions

13 June 2019

On 4 June 2019, District Judge Moore sitting at the Magistrates Court in Bexley handed down judgment in Williams v London & Quadrant Housing Trust. There were some lessons in her judgment regarding the use of experts in Environmental Protection Act 1990 prosecutions which are discussed here.

Sarah Salmon represented the successful Defendant landlord.


Ms Williams brought a prosecution under section 82, Environmental Protection Act 1990 (“EPA 1990”) against London & Quadrant Housing Trust (“L & Q”). The summons made clear that the statutory nuisance which was alleged by Ms Williams was a “severe cockroach infestation such as is prejudicial to health” (section 79(1)(a), EPA 1990).

L & Q entered a not guilty plea.

The property in which Ms Williams lived and the block within which it was situated had been the subject of visits and treatments in relation to cockroaches since around August 2016.

It was not until 13 September 2018, the Defendant received a letter of claim from Ms Williams which included concerns over a cockroach infestation. On or about 18 September 2018, a pest control company engaged by L & Q attended the property and noted there was no evidence of cockroach activity.

On or about 17 October 2018, Ms Williams’ expert inspected the property. The expert’s qualifications were set out at the back of the report. As well as experience in the “pest control sector”, the expert was awarded Level 2 in Pest Management by the Royal Society for Public Health. It was said there was a copy of the certificate in the report but it was not before the court.

The complaint to the court was dated 23 October 2018.

On 11 December 2018, L & Q’s expert carried out a visit to the property. The expert was a chartered environmental health practitioner. The report also referenced literature to which the expert had regard. At the time of this inspection, the expert concluded that the condition of the property was not prejudicial to health.

Issues at trial

At trial Ms Williams’ did not pursue a finding that the statutory nuisance existed, or was likely to reoccur, as at the date of the hearing as she had moved out of the property. The Defendant was found not guilty of an offence at the outset of the of judgment.

The remaining question was a question of costs under section 82(12), EPA 1990 (see my previous article here). Ms Williams set out to prove that the alleged nuisance existed at the date of the making of the complaint or summary application so as to recoup her reasonable costs. L & Q did not accept there was a statutory nuisance as at 23 October 2018.

The judgment

After reminding herself that Ms Williams had to prove her case to the criminal standard of proof i.e. beyond reasonable doubt, the judge held the burden had not been discharged. The judge could not be satisfied a statutory nuisance existed at the date of the complaint. The case failed.

In so finding, the judge made some important comments regarding the use of experts and language in these types of cases.

  • The word “infestation” had been used on the summons and in a lot of the documentation. The court had to look at the question of whether the situation was “prejudicial to health”. The term was defined in section 79(7), EPA 1990 as “injurious, or likely to cause injury, to health”. It was unhelpful to refer to, and use the term, “infestation”.
  • Attention must be paid to CrimPR rule 33.4 and the corresponding amended practice direction. The rules remind us that an expert’s report must give details of the expert’s qualifications, relevant experience and accreditation. The person claiming to hold the appropriate expertise must have acquired sufficient knowledge of the relevant field to render their opinion of value.
  • Attention must also be paid to CrimPR rule 19.2 which provides, inter alia, that an expert must help the court to achieve the overriding objective by giving opinion which is objective and unbiased, and within the expert’s area or areas of expertise.
  • The general rule is that witnesses should only testify in relation to matters within their knowledge. There should be a sufficiently reliable scientific basis for the expert evidence or it must be part of a body of knowledge or experience which is sufficiently organised or recognised to be accepted as a reliable body of knowledge or experience.
  • For expert opinion to be admissible it must be able to provide the court with information which is likely to be outside a judge’s knowledge and experience, but it must also be evidence which gives the court the help it needs in forming its conclusions.
  • Expert’s reports that do not comply with the rules and do not assist the judge in dealing with matters outside the court’s expertise should be reflected on: should the expert give evidence? To what extent can evidence be provided?

Applying the above to Ms Williams’ case, the judge held, inter alia, as follows.

  • Ms Williams’ expert purported to give evidence as to (i) the presence of cockroaches; (ii) the treatment used; and (iii) any health risks. He purported to give opinion evidence but his qualifications did not suggest he had the necessary expertise to give such evidence. There was no certification in the paperwork and despite giving Ms Williams a further opportunity after the two-day trial to provide the certificate it was not forthcoming.
  • Ms Williams’ expert went beyond his area of expertise when looking at the question of whether or not the circumstances were “prejudicial to health”. He was not an environmental health officer, there was no literature or research referred to and he did not carry out any appropriate tests.
  • Ms Williams’ evidence could not assist. She gave evidence as to the general nature of the problems but had not kept detailed records so that any evidence from her could have been placed before the experts.


This is an important reminder to those bringing prosecutions that they have to satisfy the court beyond reasonable doubt of a statutory nuisance and expert evidence can be crucial in this. Instructing an expert without the requisite expertise can be fatal.

For landlords, although cases like this can be a ticked off as a pleasing victory, the problem is there is no mechanism under the EPA 1990 to obtain their reasonable costs of a failed prosecution. In some circumstances, applications can be made for costs out of Central Funds (corporations cannot claim costs) and/or wasted costs; both of these are very rare.