Case Study: Alcohol intoxication and the ability (or inability) of a witness to recall events and then reliably give evidence in court.

The impact of alcohol intoxication on memory

Alcohol intoxication is a complex phenomenon that can have profound effects on various cognitive functions, including memory.

When an individual consumes alcohol, it affects the brain’s neurotransmitters and can lead to impairment in memory formation, storage, and retrieval processes.

Understanding the impact of alcohol intoxication on memory is crucial, especially in situations where memory recall plays a significant role, such as in criminal cases of sexual assault, rape offences and other crimes where there is generally no other independent witnesses, that is, where you have one person’s version against another.

Memory Accuracy v Reliability v Completeness

Memory accuracy refers to the ability of a complainant or a witness to accurately distinguish between correct and incorrect information[1].

Memory reliability is the probability that the information recalled by a complainant or witness is factually correct[2].

Memory completeness refers to a sequential account of the events, without gaps. When the memory recalled is less complete, there are fewer correct details[3].

Memory formation involves several stages, including encoding, consolidation, storage, and retrieval. Alcohol can interfere with each of these stages, leading to both short-term and long-term memory deficits. In the acute phase of intoxication, alcohol primarily impairs encoding, making it difficult for individuals to create new memories effectively. This can result in gaps or distortions in memory for events that occurred while intoxicated.

Individuals may have difficulty recalling specific details or sequences of events due to this disruption in consolidation making their testimony and version unreliable. As the blood alcohol concentration rises and the depth of intoxication increases, the proportion of accurate details from a particular narrative which can be recalled, decreases[4].

Anterograde Amnesia “Blackout or en-bloc” versus Partial or “fragmentary amnesia”

Anterograde amnesia, commonly known as a blackout or en-bloc amnesia, is characterised by the inability to form new memories following a traumatic event, such as alcohol intoxication or a head injury.

During a blackout, individuals experience a period of time where they are unable to recall events that occurred, often leading to a complete gap in memory.

Despite being conscious and engaging in activities, individuals with en-bloc amnesia cannot remember any details of what transpired during the blackout period.

Partial or fragmentary amnesia, on the other hand, involves the inability to recall specific details or portions of an event while retaining some memory of the overall experience.

Unlike en-bloc amnesia, where memory loss is complete for a certain period, fragmentary amnesia results in fragmented or incomplete memories.

Individuals may remember some aspects of an event but have difficulty recalling specific details or sequences of events.

Use of Intoxication in Legal Proceedings

In legal proceedings involving allegations of sexual assault, rape or other crimes, it is essential to assess the reliability of complainant’s testimony carefully, particularly when the witness was intoxicated at the time of the incident.

This may involve a consideration of evidence from sources other than the complainant, and even expert evidence.

Recently in a rape trial where Mark Williams represented one of our clients, we led evidence from a medical expert on the issue of fragmentary amnesia.

The jury were informed by our expert doctor, that the complainant suffered fragmentary amnesia and subsequently was able to make decisions, and engage in conversation, yet might not have been able to reliably recall any details.

The jury were also informed that the complainant would likely have been disinhibited, especially with respect to certain decision-making.

Final Thoughts

The profound effects of alcohol intoxication on memory underscore the complexity of assessing the reliability of the complainant’s testimony in cases of sexual assault, rape and other crimes.

Understanding the intricate interplay between alcohol-induced memory impairment and the ability of complainants and witnesses to recall events accurately is essential for legal professionals when representing their clients.

While alcohol intoxication can significantly impair memory encoding, consolidation, and retrieval processes, it is imperative to approach testimony from intoxicated individuals with scrutiny.

Legal proceedings must take into account the multifaceted nature of memory formation and consider corroborating or expert evidence to establish a comprehensive understanding of the events in question.

Seek Legal Advice

Given the intricate legal and psychological considerations involved, individuals affected by alcohol-related memory impairment should seek expert legal advice from us in order to navigate this complex issue effectively to ensure defences are raised and the evidence against a person is tested and scrutinised as far as the law permits.

Contact our dedicated team of criminal lawyers in Brisbane and the Gold Coast to book an initial consultation and get help and advice on your legal matter.

 

[1] Altman et al; Witness memory for events and faces under elevated levels of intoxication. Memory. 2018;26 (946-959).

[2] Ibid.

[3] Ibid.

[4] Altman et al; Witness memory for events and faces under elevated levels of intoxication. Memory. 2018;26 (946-959).