After the second terrorist attack on day 6, a scanner is set up to search those who have an incorrect weight in case they are suicide bombers or smugglers trying to sneak weapons or contraband across the border. The scanner is also used to verify the sex of the entrant if their stated sex does not seem to match their appearance.
On the first day the scanner is used (day 7), there is an initial rule that states that any entrant from Kolechia must be searched in case they carry any weapons that can be used against any innocent Arstotzkans. Failure to do so results in a citation. The rule is later repealed due to the Kolechian government filing a complaint but the search option remains in use for the rest of the game.
Even if a search is available to clear a discrepancy, the player is not required to perform the search and can instead, without a citation, deny the entrant outright based on the discrepancy that enabled the search option. Unless the reason for denial stamp is in play (since day 18), it is not even necessary to interrogate about the discrepancy. Thus all Kolechians can be denied on day 7 without searching them or being cited for violations; the rule is implemented so that having a Kolechian passport is a "discrepancy". Once the search is performed, the discrepancy may be cleared, in which case the entrant cannot be denied entry based on the cleared discrepancy. Since each entrant may only have discrepancy in their papers and one misstatement regarding reason for entry or duration of stay, clearing a discrepancy by searching usually makes the entrant clear for entry.
The images from the search scanner will show nudity in the form of genitals for males and breasts for females if the option is turned on. In other cases it just shows their underwear and bra.
The scanner technology represents an anachronism within the game's setting of 1982: full body scanners of this kind were not widely deployed till 2007, and were not even invented till the early 1990s.