In the United Kingdom, a hybrid instrument (or hybrid bill) is a public bill proposing a law which affects the private interests of a particular person or organisation. It is generally initiated by the government on behalf of non-parliamentary bodies such as local authorities and is treated like a private bill for the beginning of its passage through the Parliament of the United Kingdom. This gives individuals and bodies an opportunity to oppose the bill or to seek its amendment before a select committee in either or in both Houses. The bill is then treated as a public bill.
The use of hybrid instruments originated as part of the parliamentary procedure of the United Kingdom Parliament, but the procedure is also occasionally used by other parliaments and assemblies set up on similar lines to that of Westminster.
Historically, hybrid instruments have often been used by government on behalf of railway companies and transport agencies to obtain authorisation for major projects deemed to be in the national interest, but which would affect a large number of private interests.
Statutory instruments can also be hybrids. When opposed, such instruments are referred to the Hybrid Instruments Committee to report to the House on whether a select committee should be appointed to consider the petition or petitions against the instrument.
In Canada, they are specifically disallowed by Beauchesne's Rules and Forms of the House of Commons of Canada, which states that "According to Canadian standing orders and practice, there are only two kinds of bills – public and private. The British hybrid bill is not recognized in Canadian practice."