Before doing specific things, like charging you with a criminal offence or conducting a search, the police must have reasons to believe you:
- could have committed a criminal offence, or
- have evidence or weapons related to a criminal offence.
Their reasons must be based on reliable information. Having reasonable grounds is more than having a hunch or suspicion, but less than being able to show a balance of probabilities.
"Reasonable and probable grounds" and "reasonable grounds" mean the same thing.