Other such offences include betraying party loyalties. An example of this during John Major's government was when nine Conservative MPs had the whip removed after voting against the government on its stance on the Maastricht Treaty, becoming known as Eurosceptics. In practice they remained Conservative MPs supporting the government on other issues. Sir Bill Cash, John Redwood and Iain Duncan Smith are still Conservative MPs. This was also the only time when MPs who were being whipped were cooperating with the opposite side's whips. In most cases the 'pairing' system enables one from each side to cancel out the other's vote if absent simultaneously. Yet despite the whip, individuals are entitled to vote according to their own beliefs, particularly when there is a "free vote" on a matter of conscience. There are some cases in which the whip is removed because an issue is a matter of conscience. These include adoption, religion and equal opportunities. The impact of a whip being imposed on a matter of conscience can be damaging for a party leader. One such case was that of Iain Duncan Smith, who imposed a three-line whip against the adoption of children by unmarried couples (which at the time meant gay couples could never adopt). Several Conservative MPs voted against the official party line, and Smith's authority was weakened.