Customs officers are government employees who work in airports, docks, and other points of entry to the country. Their primary duties are to check that people are entering and leaving the country legally and that they do not bring illegal substances into the country, such as drugs or weapons. As a customs officer, your responsibilities include checking traveler passports and customs documents for authenticity, searching luggage or cargo, and question any traveler found with suspicious or unlawful goods. In cases where you find illegal substances or suspicious activity, you may be called to testify about your observations in a criminal trial.