Legal Context for Evidence


An investigation of an incident under the RMA is a systematic inquiry undertaken in order to establish verifiable facts. In relation to an offence, the aim is to determine what happened (including the causes and effects of the incident involved), who did what, and why.

Many factors may be involved in an offence, especially in terms of the causes of the act or omission in issue. None of these factors should be ignored in an investigation. It is important that incidents are investigated thoroughly and the correct procedures are followed. If mistakes are made, or the correct procedures are not followed, the subsequent enforcement action may fail. For example, the evidence gathered during the investigation may be excluded from consideration by the Court.

The objectives of a good investigation include the following:

  1. assurance that an offence has or has not occurred (i.e. all tenable theories have been investigated and assessed, and all reasonable inquiries undertaken)
  2. disclosing a persuasive case for a guilty plea (i.e. avoiding the unnecessary costs of a defended hearing)
  3. making good decisions to prosecute or otherwise
  4. efficiency: do it once, do it properly.

The Evidence Act 2006 (EA) has become the starting point for determining the admissibility of evidence. The existing common law remains applicable, but only to the extent that it is consistent with EA's provisions, including its purpose and principles (refer 10(1) of the EA). The common law will continue to be of importance in a number of areas, for example in assessing whether evidence has been fairly and properly obtained.

Proof and evidence

Offences under the RMA can result in criminal proceedings (i.e. prosecution). The relevant Court determines the facts based on the evidence before it, and also whether those facts justify the legal action taken or sought. The hearing may be before a judge alone, or a jury depending on the offence involved.

The prosecuting authority has to prove that the defendant committed the offence, which is commonly referred to the 'burden of proof ' principle. If there is reasonable doubt as to whether the evidence proves that the defendant committed the offence, the 'burden of proof 'has not been met and the defendant will be acquitted.

Generally, the prosecuting authority must also prove that any defences raised by the defendant do not apply. However, in some cases the statute which prescribes the offence shifts the burden of providing that a defence applies onto the defendant. For example, defences under the RMA and Building Act 2004 may be upheld if the defendant proves the stated elements (s341 of the RMA, s388 of the Building Act 2004).