Lawyer lips or lawyer tabs (a type of "positive retention device"), a nineteenth century invention, are tabs fitted to the fork ends on the front fork of bicycles sold in some countries (particularly the U.S.) to prevent a wheel from leaving the fork if the quick release skewer comes undone. They were reintroduced in response to lawsuits supported by experts including John Howard, in cases where incorrectly adjusted quick release wheels came out of the forks. Lawyer tabs are designed to compensate for the fact that many riders do not know how to operate a quick release properly: some riders treat them as a folding wing nut, and others do not tighten them enough for fear of snapping them or shearing the skewer (both are not likely given the normal range of human strength, and the mechanical advantages involved, as long as the skewer is not damaged or flawed).