The Laws of Shabbos part 5 vol.4, no.16
The sanctity of Shabbos places certain limitations on the Jew’s activities during the Shabbos. Not only may he not perform many acts himself, but he may not ask a gentile to perform those prohibited acts in his stead. A Jew is also not allowed to ask a gentile during the week to perform a prohibited act on an upcopming Shabbos.
Not only is it prohibited to ask a gentile directly to perform a task the Jew is prohibited from doing, it is also prohibited to hint to the gentile in a direct way that he needs a prohibited task performed. For example, a Jew cannot say to a gentile on Shabbos "If you turn off my lights everyone would be happy." In this example the Jew has not asked the gentile outright to turn off the light but has hinted to him by mentioning the act of turning off the light. It is also prohibited to hint in a direct way with body motions1, like pointing to the light switch and pantomiming the motion for turning off the light.
However, it is permitted to hint to a gentile in an indirect way that a prohibited task must be performed.2 For example, a Jew may say to a gentile "It is difficult to sleep in such a bright room." In this way the gentile might take the initiative on his own and perform a favor for the Jew by turning off the light. This is permitted because the Jew never mentioned turning off the light.
A Jew may also hint indirectly to a gentile by saying "The light is too dim in this room to read properly" so that the gentile will do the favor of increasing the light in the room. However, if the room was totally dark this would not be permitted since one cannot derive positive benefit from a prohibition performed for his sake.3
One is permitted to request a gentile directly to perform even a Torah prohibition for the needs of a not seriously ill person.4
A Jew is allowed to ask a gentile to perform a Rabbinic prohibition for the sake of a mitzvah, or in cases of great need. For example, if food needed to be transferred for a Shabbos meal through an area which is not a real rashus harabim and which does not have an eruv, one could request a gentile directly to move it.5
1) Chayei Adam62:2 2)Mishna Berura 307:76 3) ibid 4)MB 328:47 5)MB 325:60
