Can I refuse a police search if they don't have a warrant?

In Plain English

It depends on the situation. Generally, police need a warrant to search your property. However, there are exceptions. For example, if you're in a public place or at school and have a knife, a police officer can search you without a warrant. Also, if a police officer believes that you have something related to a crime and that searching you immediately is necessary to prevent the evidence from being hidden or destroyed, they can search you without a warrant. If you've been arrested, police have more extensive search powers.

Detailed Explanation

Whether you can refuse a police search if they don't have a warrant depends on the circumstances and the specific powers granted to police under relevant legislation.

Here are some situations where police may conduct a search without a warrant:

Knife Possession in Public Place or School: According to the Criminal Procedure Act 2007 (NI), if a police officer finds a person in a public place or school in possession of a knife, the officer can conduct a frisk search or an ordinary search of the person and seize the knife. The officer must provide evidence that they are a police officer (unless in uniform) and inform the person of the reason for the search (section 55).
Emergency Searches: Under the Criminal Procedure Act 2007 (NI), section 69 outlines the power to stop, search, and detain people without a warrant if a police officer suspects, on reasonable grounds, that a person is carrying something related to an indictable offense or a stolen item, and it is necessary to search them immediately to prevent the concealment, loss, or destruction of the item, and the circumstances are serious and urgent.
Search During Arrest: The Criminal Procedure Act 2007 (NI) grants police the power to search a person who has been arrested. Section 83 allows a frisk search of an arrested person to ascertain whether the person is carrying any seizable items. Section 84 allows an ordinary search of an arrested person if the police officer suspects on reasonable grounds that the person is carrying evidential material or a seizable item. Section 86 allows for an ordinary search of a person brought to a police station following arrest, and frisk or ordinary search of a person in lawful custody if a police officer of the rank of sergeant or higher suspects on reasonable grounds that the person is carrying evidential material or seizable items.
Emergency search for tainted property: Under the Proceeds of Crime Act 1987, section 38 allows a police officer to search a person or enter premises to search for tainted property if the officer believes on reasonable grounds that it is necessary to do so to prevent the concealment, loss, or destruction of the property, and the circumstances are so serious and urgent that they require the immediate exercise of the power without a warrant.
Screening at Questioning Warrants: Under the Australian Security Intelligence Organisation Act 1979, section 34D allows a police officer to request a person entering a place where someone is appearing under a questioning warrant to undergo a screening procedure, produce items for inspection, or undergo a search if the officer suspects on reasonable grounds that the person is carrying a dangerous item or communication device.
Emergency Search for Cultural Heritage: Under the Protection of Movable Cultural Heritage Act 1986, section 32 allows an inspector to search a person or enter premises if the inspector believes on reasonable grounds that the person is carrying something forfeited or connected with an offense against the Act, and it is necessary to do so to prevent the exportation or importation of that thing or the concealment, loss, or destruction of any thing forfeited or connected with an offense against this Act, and the search or entry is made in circumstances of such seriousness and urgency as to require and justify immediate search or entry without a warrant.

In summary, while a warrant is generally required for a police search, there are several exceptions where police are authorized to conduct searches without one, particularly in situations involving urgency, public safety, or following an arrest.