A mobile phone can contain years of private messages, photographs, emails, financial information and location data. If police seize your phone and ask for the PIN, it can be difficult to know whether you have any choice but to provide it.

A recent South Australian District Court decision confirms that police may ask for a PIN, but a person ordinarily has the right to refuse to provide it. Police must not undermine that right by making the person believe that there is no choice but to hand over their PIN.

The decision also examined two vehicle searches prompted partly by claims that the accused appeared nervous, sweaty or evasive. The Court found that neither search was supported by a reasonable suspicion.

Although police allegedly found drugs and evidence of drug dealing, all of that evidence was excluded from the accused’s trial.

Do You Have to Give Police Your Phone PIN?

A person whose phone has been lawfully seized ordinarily has the right to refuse to provide the PIN.

The right to silence is not confined to refusing to answer questions about an alleged offence. It can also include refusing to provide information that may allow police to obtain incriminating evidence.

There may be circumstances in which police have a particular statutory authority, warrant or court order affecting access to a device. The precise position therefore depends on the powers being exercised and the circumstances of the investigation. However, the fact that police have possession of a phone does not, by itself, mean its owner must disclose the PIN.

For a broader explanation of when police can lawfully search a person, vehicle or property, see our comprehensive guide to police search powers in South Australia.

Can Police Ask You to Unlock Your Phone?

Police can ask a person to unlock a phone or provide its PIN, but the person must be given a genuine choice about whether to disclose it.

In the recent case, police conducted recorded interviews with the accused at a house and later at a police station. After the formal interview had concluded, the recording devices were switched off. A police officer then asked for the PIN to the accused’s phone.

The accused asked, “Do I have to?”

The officer replied that he did not, but added that police would send the phone away to be accessed anyway and that refusing might simply make the process take longer.

The Court found that this exchange likely conveyed that the accused had no meaningful choice. He may have understood that police would gain access regardless of what he decided, making refusal appear pointless.

What Is a Police Caution?

A police caution is a formal warning that a person does not have to say or do anything in response to police questioning, although anything the person says or does may later be used in evidence.

The purpose of the caution is to ensure that a person understands the right to silence and can make a genuine choice about whether to answer questions or assist police.

A caution does not prevent police from continuing their investigation. Nor does it necessarily prevent them from asking further questions. It is intended to make clear that the person is not required to answer those questions merely because a police officer has asked them.

Whether an effective caution was given can become important if police later seek to use the person’s answers or actions as evidence.

Does Giving a Police Caution Make the Request Lawful?

A caution will not necessarily protect a person’s rights if the words or conduct that follow it suggest there is no real choice.

In this case, the officer believed he had cautioned the accused before asking for the PIN. However, the conversation was not recorded and there was no independent evidence establishing that a proper caution had been given.

The Court also found that, even if the accused had been cautioned, the officer’s response would have undermined or reversed it. Telling someone that they do not have to provide a PIN, while also suggesting that police will access the phone anyway, may make the supposed choice meaningless.

The Court observed that the exchange likely conveyed to the accused “that he had no choice but to hand over his PIN”.

The question is therefore not simply whether the usual caution was recited. The surrounding circumstances must show that the person genuinely understood that they could refuse.

That was particularly important because the accused had already declined to answer questions during the formal interview. The Court considered that a strong indication that he would also have refused to provide his PIN if his rights had been properly preserved.

Can Police Access Your Phone Without the PIN?

Police may have technical or legal means of attempting to access a seized phone without the owner’s assistance. However, some phones are secure enough to stop police from accessing them without the PIN.

That does not mean a person is required to make the process easier by voluntarily providing the PIN. Nor does the possibility that police may gain access through another method remove the person’s right to decide whether to answer the request.

In the recent case, it did not matter that police might eventually have accessed the phone through their digital evidence specialists. What mattered was how they actually obtained the PIN and whether the accused had been permitted to make a genuine choice.

The messages discovered on the phone allegedly indicated drug dealing. Despite their significance to the prosecution case, the Court excluded them from the trial.

Can Police Search a Car Because Someone Appears Nervous?

Perceived nervousness alone will not ordinarily provide a reasonable basis for police to search a person or vehicle.

A further question the Court had to consider was whether police had lawfully searched two vehicles in which the accused was a passenger.

Before the first search, a police officer saw the accused run from a vehicle into an address associated with drug activity. The vehicle left shortly afterwards and was later stopped by police. The officer knew the accused and had information suggesting that both occupants had previously been connected with drug trafficking.

However, the officer accepted that this information was not enough, by itself, to justify a search for drugs.

According to the officer, the driver then appeared nervous. He described her as avoiding eye contact, stuttering and swallowing. Police relied on that perceived behaviour, together with the information they already held, to search the vehicle and the accused.

However, the Court reviewed the police footage and could not see the nervousness described by the officer. It also observed that the driver had an obvious alternative reason to be uncomfortable: her driver’s licence had been cancelled.

The Court commented that there may be “many reasons why someone may be nervous in the presence of police”. Even if the officer had perceived some nervousness, the Court found that he had associated it with illegality too quickly rather than considering other plausible explanations.

The Court concluded that there was no evidence that the driver was nervous. It found that the search of the vehicle and the accused was unlawful.

Are Sweating and Avoiding Eye Contact Grounds for a Search?

Sweating, avoiding eye contact or appearing evasive may form part of the surrounding circumstances, but those behaviours do not automatically establish a reasonable suspicion.

The second search occurred after police saw another vehicle leave an address they had been observing. Police followed the vehicle and stopped it to conduct an alcotest. The driver returned a negative result.

Before stopping the vehicle, police did not believe they had enough information to conduct a search for drugs. Once the vehicle had been stopped, however, one officer described the driver as nervous and the accused as sweaty, evasive and unwilling to make eye contact. Another officer described the accused as sweating “profusely”.

Police relied on those observations to search the vehicle.

The Court found that the additional observations did not provide a reasonable basis for the search. It was dark, the officers’ descriptions were inconsistent and the footage did not support several of their claims. One officer described profuse sweating, while the more experienced officer made no equivalent observation.

The Court noted that “sweating on its own does not necessarily point to recent drug use”. It also found no sign of nervousness in the footage of the driver’s interaction with police.

The Court was concerned that police already wanted to identify the occupants of the vehicle and, after stopping it, may have been keen to find something that would permit a search. It did not find that the officers were deliberately lying, but it was not satisfied that their later recollections accurately described what had occurred.

Police needed something more than sweating, perceived nervousness and the information they already possessed. The Court ruled that the second search was also unlawful.

What Makes a Police Suspicion Reasonable?

A reasonable suspicion must be supported by objective circumstances rather than a hunch, speculation or a tenuous chain of assumptions.

Police can consider the whole situation. Relevant circumstances might include reliable intelligence, observations of particular conduct, items visible in a vehicle or information provided by another person. Facts that appear innocent when considered separately may sometimes become significant when considered together.

However, previous involvement with police, association with a particular person or address, nervous behaviour and minor eccentricities do not automatically justify a search. The connection between the observed facts and the suspected offence must be reasonably substantial.

The Court explained that the requirement for reasonableness distinguishes a lawful search power from “a virtual limitless power to search” based merely on an officer’s suspicion.

Without that requirement, almost any ordinary behaviour could be interpreted as suspicious after the event.

Our guide to police searches in South Australia discusses reasonable suspicion in greater detail and provides further examples of searches that South Australian courts have found unlawful.

Why Are Police Footage and Notes So Important?

Body-worn footage and contemporaneous notes made by police can reveal whether the grounds later given for a search existed at the time.

In both incidents, the Court compared the officers’ evidence with the available footage. It found no visible support for several of the claimed observations of nervousness, sweating or evasiveness.

There were also deficiencies in the notes made by police. Important observations were either not recorded or were described differently by the officers involved. The conversation in which the phone PIN was obtained had not been recorded, either on a camera or in the police officer’s notes, even though earlier interactions had been.

A Court may be asked to decide the legality of a search months or even years later. Footage and notes made at the time can be far more reliable than a person’s later recollection. Where the objective record contradicts the stated justification for a search, it can substantially weaken the prosecution’s position.

Is Evidence From an Unlawful Search Automatically Excluded?

Evidence obtained unlawfully is not automatically excluded from a criminal trial.

The Court must balance competing public interests. There is a public interest in admitting reliable evidence and prosecuting serious offences. There is also a strong public interest in ensuring that police obey the law and respect the rights of the people they investigate.

The purpose of excluding evidence is not to punish police. It is to prevent courts from condoning or encouraging unlawful methods of obtaining evidence.

In this case, the prosecution argued that the evidence was compelling and that the alleged drug trafficking was serious. Excluding the drugs and phone messages would substantially undermine the prosecution case.

Nevertheless, the Court found that the searches were not supported by reasonable suspicion and that the accused’s right not to incriminate himself had been undermined when police obtained his PIN. Those considerations outweighed the importance of the evidence to the prosecution.

The drugs found during both searches and the evidence obtained from the phone were excluded from the trial.

For a more detailed discussion of how courts deal with evidence obtained during an unlawful search, see What Happens if the Police Conducted an Unlawful Search?.

What Should You Do If Police Want to Search Your Car or Access Your Phone?

If police say they intend to conduct a search, do not physically resist or obstruct them. Whether the search was lawful can be challenged later.

You can calmly state that you do not consent to the search but will not hinder police. If asked questions or requested to provide a phone PIN, you can say that you wish to exercise your right to silence and obtain legal advice.

The legality of a search and the admissibility of any resulting evidence will depend on exactly what occurred. The officer’s stated reasons, body-worn footage, notebook entries, applicable legislation and words exchanged at the scene may all become important.

If you have been charged after police searched you, your vehicle or your phone, obtain legal advice as soon as possible. Evidence that appears decisive may still be challenged if police did not have lawful grounds for the search or failed to respect your rights when obtaining it.

R v Ayres [2026] SADC 84 (17 July 2026)