It isn't really possible to identify the "usual defences" in the abstract, because mandatory reporting offences are relatively new, technical in nature, and different in each jurisdiction. Also, they are usually minor offences which involve very sensitive information. Even when the facts are disputed, it will often be in the interest of all parties for these offences to be dealt with quietly in a regulatory tribunal or magistrates' court, rather than appealed to a higher court which publishes its decisions.

However, I am aware of one case which analyses an attempted defence to a mandatory reporting charge in some detail: Webb v Tang [2021] WASC 344. The appellant was a teacher who was convicted of failing to report a belief on reasonable grounds that a child had been the subject of sexual abuse, a mandatory reporting offence introduced in Western Australia in 2008. He appealed to the state Supreme Court, including on the ground that the verdict was unsafe and unsupported by the evidence, so the decision includes a lot of detail about how this offence could potentially be defended in Western Australia, and perhaps other jurisdictions.

The teacher was on an international trip arranged by a school sports team. One of the students told the teacher that he had been sexually assaulted by some other students the night before. The student refused to name the perpetrators and said he wanted nothing done about it. The teacher did not report this. Explaining his failure to report at a later date, the teacher said "it's not that I didn't believe him, but … I just didn't think that the group would – that that could have happened." The teacher argued that he did not believe on reasonable grounds that sexual abuse had occurred. However, the court found that the prosecution had established the required state of mind. The teacher received a spent conviction and was fined $1,200.

The teacher did not rely on the statutory defence in s 124B(3) (belief that the issue had already been reported to, or was being dealt with, by the authorities) and there was no generic "reasonable excuse" defence in the relevant statute. However, it is likely that other mandatory reporting offences will also involve disclosures that come as a surprise to the mandatory reporter and leave them with some uncertainty about the meaning or credibility of the disclosure. In these cases there will be scope for the mandatory reporter to give evidence about their own state of mind and claim that they did not know or believe the information required to trigger the reporting obligation.

It isn't possible to identify the "usual defences," because mandatory reporting offences are relatively new, technical in nature, and different in each jurisdiction. Also, they are usually minor offences which involve very sensitive information. Even when the facts are disputed, it will often be in the interest of all parties for these offences to be dealt with quietly in a regulatory tribunal or magistrates' court, rather than appealed to a higher court which publishes its decisions.

However, I am aware of one case which analyses an attempted defence to a mandatory reporting charge in some detail: Webb v Tang [2021] WASC 344. The appellant was a teacher who was convicted of failing to report a belief on reasonable grounds that a child had been the subject of sexual abuse, a mandatory reporting offence introduced in Western Australia in 2008. He appealed to the state Supreme Court, including on the ground that the verdict was unsafe and unsupported by the evidence, so the decision includes a lot of detail about how this offence could potentially be defended in Western Australia, and perhaps other jurisdictions.

The teacher was on an international trip arranged by a school sports team. One of the students told the teacher that he had been sexually assaulted by some other students the night before. The student refused to name the perpetrators and said he wanted nothing done about it. The teacher did not report this. Explaining his failure to report at a later date, the teacher said "it's not that I didn't believe him, but … I just didn't think that the group would – that that could have happened." The teacher argued that he did not believe on reasonable grounds that sexual abuse had occurred. However, the court found that the prosecution had established the required state of mind. The teacher received a spent conviction and was fined $1,200.

The teacher did not rely on the statutory defence in s 124B(3) (belief that the issue had already been reported to, or was being dealt with, by the authorities) and there was no generic "reasonable excuse" defence available. However, it is likely that other mandatory reporting offences will also involve disclosures that come as a surprise to the mandatory reporter and leave them with some uncertainty about the meaning or credibility of the disclosure. In these cases there will be scope for the mandatory reporter to give evidence about their own state of mind and claim that they did not know or believe the information required to trigger the reporting obligation.