Mishnah Berurah — משנה ברורה

Modestly at night - That is to say, that one should not expose himself [at night] more than he does during the day, and one should not expose himself [when in the bathroom] until he is sitting, and other matters similar to these. Because before Hashem, Blessed is He, darkness is like light. But one need not distance himself [from others]. If there is nobody there, one can defecate in the streets, as long as he is careful that he is not defecating where people walk, lest they become filthy because of him. However, if there is someone there, even a non-Jew, it is prohibited to defecate before them. All of this is regarding defecating, but to urinate is permitted, even during the day in front of many people, if he has no other place to go. This is even permitted in front of a woman, since there is danger if he holds himself back. A woman may not even urinate in front of a baby, since there exists an element of audacity in this. However, when she urinates off to the side where she is not directly in front of others, there is no prohibition.