Police questioning can be either formal (at a police station with a record of interview made) or informal. Formal interviewing usually occurs after an arrest has been made, however, informal questioning can occur under a wide range of circumstances (such as when pulling over a vehicle in relation to a traffic offence). Young people are particularly likely to be subject to informal questioning as it is common practice for police to stop and question them in public.

There are certain rules that police must follow when they intend to interview a person with complex communication needs. See Interviewing Suspects with Complex Communication Needs.

Right to remain silent

The right to remain silent is a fundamental right for all people when being questioned by police. It stems from the basic common law principle that it is the state’s role to prove the guilt of an accused person, not the accused’s. Importantly, no negative conclusion can be drawn from an accused relying on their right to silence when the matter goes before the courts.

An accused person who does not wish to say anything to the police should make that clear. They must state their name and address and say to the police something like "I do not wish to say anything further".

If the police ask further questions, the accused person should repeat "I do not want to say anything". If this is the advice received from a lawyer or legal adviser, they should say "I do not wish to answer any questions on the advice of my legal adviser".

In reality, invoking the right to remain silent can be extremely difficult. In high pressure situations such as a police interview people often feel an overwhelming need to provide information in the belief this will assist them and that the police will go easier on them because of their cooperation. It is also difficult for most people to assert themselves when dealing with people in authority. In addition, interviews will always start with questions about name and address which must be answered. At this point the accused person has already been placed in a position of having to cooperate and it can be very difficult to invoke the right to refuse to answer questions and be ‘uncooperative’ from this point onwards.

There are certain police questions that must be answered. See Being questioned for more information about questions that must be answered and the penalties for non-compliance.

The risks of answering some questions but not others

An accused person who decides to exercise their right to silence should maintain that position and not answer questions selectively. There are significant risks in answering some questions and not others that may not be obvious on the face of the questions, and the police may be able to use the record of interview against the accused in court.

An accused person who wishes to cooperate with police or make a statement should speak with a lawyer first. That lawyer may be present when the accused speaks with police and may help prepare their statement. It may be in a person’s best interest to make a statement, such as where a person has a valid explanation. However, this should only be done after obtaining legal advice.

Where police fail to observe proper procedure

If the police do not tell an arrested person that they have the right to remain silent, they may not be able to use any evidence gained through questioning against the person.

Should the police overstep the mark in interviewing a person, again any evidence gained from their questioning may be excluded. For example, if a person indicates that they do not want to answer questions but the police ask more questions, or use an inducement such as promising bail in return for cooperation, and answers are eventually given, those answers may be excluded at trial.

Verbal admissions

The police are experts at getting information from people. They may indicate that the process will be smoother with cooperation, that bail will be granted if a statement is made, or that an alleged co-offender has already given a statement. Any incentives offered by the police should be ignored if the person does not wish to answer questions.

Written and verbal statements can be used in evidence. Any conversation with the police can be used in evidence. There is no such thing as an "off the record" interview with police.

Police can also listen to and note down conversations a person has with anyone else, except a lawyer, and use it later in evidence against the person. Care should be taken when calling friends or family or meeting with them in police custody.

Record of interview

Every police interview with a person accused of committing an indictable offence is required to be recorded. This should be by video (audio visual) but can be an audio or written record if a video recording is not reasonably practicable [Summary Offences Act 1953 (SA) s 74D]. The record of interview may be presented as evidence in court if the matter proceeds to trial.

An accused who does not wish to answer questions may be asked to state this on the audio visual or audio record. The police cannot force a person to be recorded and a person who does not wish to be taped should tell this to the police. If a person refuses to allow the interview to be recorded, the police may ask them to sign a form confirming the refusal. This is not unusual.

Where a written record is made of an interview, the accused will be asked to read and sign it. There is no obligation to read or sign a record of interview. An accused should always read the record of interview before signing and can refuse to sign if the police will not allow them to read it. An accused who does not agree with information contained in the record of interview should ask that it be corrected.

Even if unsigned, if an accused indicates to the court that an interview was given voluntarily and is accurate, it may be admitted at trial.

An accused person has a right to view the recording of their police interview and obtain a copy of the audio [s 74D(4) - (6)].

When a vulnerable witness is being interviewed as a witness to a serious offence against the person (such as murder, manslaughter, criminal neglect, a sexual offence, abduction, blackmail, unlawful threats to kill, and some other offences [see s 74EA]), police must make an audio visual recording of the interview [s 74EB]. Vulnerable witness in this instance refers to a child of or under the age of 14 years or a person with a disability that adversely affects the person’s capacity to give a coherent account of their experiences and answer questions rationally [s 74EA].