or protect their sources in court or elsewhere, so that compulsory testimony is wrong. However, there is an exception to the right to use and disseminate knowledge within one's head, if it was procured from someone else as conditional rather than absolute ownership. Rothbard also discusses the inviolability of contractual copyright and explains that a violation of such copyright is an equivalent violation of contract and theft of property. Furthermore, no one can acquire a greater property title in something than has already been given away or sold. For instance, Brown may retain the right to sell his design of mousetraps, and sell to Green only the right to use the mousetraps, but not to sell them. So, if Green or anyone else were to sell that design of mousetraps, it would be a violation of Brown's property rights and prosecutable as theft. Rothbard acknowledges that there may be difficulties in enforcing property rights in some cases, particularly when products are easier to replicate. Rothbard also defends the right to blackmail, arguing that the right to disseminate or not disseminate knowledge is derived from the general property right in one's person and knowledge. As such, one has the right to receive payment in exchange for not disseminating such knowledge. If blackmail were illegal, it would encourage people to disseminate derogatory information. Rothbard argues that the vilification suffered by the blackmailer is unjustified compared to the gossip or blabbermouth, who is usually dismissed with slight contempt. Rothbard poses questions about the outlawry of blackmail contracts, such as whether it should be illegal for Jones to offer to purchase Smith's silence, and whether it should be illegal for Smith to let Jones know he has the information and intends to publish it. Bribery, boycotts, and contracts Chapter 17, "Bribery", argues that there is nothing inherently wrong with the act of giving a bribe, as it is simply a way to lower prices and gain contracts. The real problem lies with the person receiving the bribe, who is violating their contractual obligation to act in the best interest of their employer. Therefore, only the taker of a bribe should be prosecuted, not the giver. This applies to situations such as payola and plugola, where a bribe is given to influence the playing or advertising of certain products. The violator of property rights in these situations is the person who accepts the bribe, not