Catechism of the Catholic Church §2408 — excerpt
The seventh commandment forbids theft, that is, usurping another's property against the reasonable will of the owner. There is no theft if consent can be presumed or if refusal is contrary to reason and the universal destination of goods.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: GS 69 # 1