Reasonable and probable grounds in Australia

Reasonable and probable grounds have evolved from common-law judgments, employing judicial discretion to make a balanced ruling.

[12][16] Police, on reasonable and probable grounds, can exercise discretionary powers including arrest, searches, requests for identity and investigating terrorist activity.

[19] This is preserved by statutory reforms, creating a legal standard[4] in section 99 of the Law Enforcement (Powers and Responsibilities) Act 2002 (NSW).

[21] Similar to the power of arrest, police can search a person, vehicle or premises without a warrant on reasonable and probable grounds.

[3] The reasonable grounds by which a police officer exercises the search of a person, vehicle or premises is legitimized for the purposes of discovering (and preserving) evidence.

[4] This power, less contentious than arresting or searching without a warrant, is subject to reasonable and probable grounds to protect the human rights to privacy and dignity.

[28] An incorrect presumption by police officers of reasonable and probable grounds for the exercise of power risks the encroachment or violation of those rights.

[29] The death of Beto Laudisio involved inappropriate, disproportionate use of force in the police officers' arrest Roberto Curti.

The legitimacy and legality of the reasonable and probable grounds to use force in the attempt to arrest Curti was undermined by irrationality and poor assessment of the situation.

The most prominent reform, in 2013, narrowed the grounds of reasonableness and probability with a twofold test which police officers must satisfy before making an arrest without a warrant.

[4] In the United States, the doctrine of probable cause governs the exercise of police powers and is argued as differing from reasonableness in preventing random and unnecessary searches.