In Queensland, drug driving is illegal. Which of the following statements about drug driving is correct?

1. Only illicit drugs are illegal — prescription medications do not affect your ability to drive legally
2. You can only be tested for illicit drugs at a crash scene, not during routine policing
3. Police can conduct roadside drug tests for certain illicit substances, and driving impaired by any drug — including prescription medication — is an offence
4. The rules only apply when the drug affects your BAC reading