Private Member's Bill

A private member's bill in a parliamentary system of government is a bill (proposed law) introduced into a legislature by a legislator who is not acting on behalf of the executive branch. The designation "private member's bill" is used in most Westminster System jurisdictions, in which a "private member" is any member of parliament (MP) who is not a member of the cabinet (executive). Other labels may be used for the concept in other parliamentary systems; for example, the label member's bill is used in the Scottish Parliament and in the Parliament of New Zealand. In presidential systems with a separation of the executive from the legislature, the concept does not arise since the executive cannot initiate legislation, and bills are introduced by individual legislators (or sometimes by popular initiative).

In the Westminster System, most bills are "government bills" introduced by the executive, with private members' bills the exception; however, some time is set aside in the schedule for reading such bills. They may be introduced by non-ministerial MPs from government-supporting parties (backbenchers), by members of opposition parties (frontbencher or backbencher), or by independents or crossbenchers. The United Kingdom parliament has a long history of enacting private members' bills. In contrast, the Oireachtas (parliament) of the Republic of Ireland rarely passes private members' bills, with the overwhelming number of bills being passed being introduced by members of the cabinet.

...
Wikipedia