A San Francisco father says park rangers questioned him while he was practising tennis with his young children at a public court, warning that he might need a permit to teach lessons. The incident has drawn attention because it raises questions about how rules on commercial instruction are applied when parents are simply helping their own children play sport.

Sam Dogen said he had intended to spend an afternoon playing tennis with his family when rangers approached him. According to the report, he was told he could face a $192 fine for teaching tennis without a permit at the city park; the account does not indicate that a fine was issued.