The process of law making involves a rigid set of stages, starting with the 'origins of a bill'. This 'bill' (as it is known before becoming a 'law') may have originated from the party's manifesto that won them the election, or it may be a proposed bill written by the government when actually in power. It may instead be a law that the civil service now wants to implement.
This 'bill' is drafted up. Civil servants will do this, and the prime minister will be kept informed of progress wherever necessary. Once this has been done, the parliamentary draftsmen will put the bill into correct legal language.
The government business managers then decide whether the bill is introduced into the House of Commons, or the House of Lords. The former is the more likely route, but in both cases it is a five stage process.
It runs as follows. The first reading is just a formality, where the bill is read out. The second reading involves a debate to see if the bill is actually a good idea or not. At the committee stage, in the House of Commons, the bill goes to a Public Bill Committee that involves 16 - 50 MPs who know about the subject matter. Detailed consideration is given to the bill. If the bill was introduced into the House of Lords instead, the whole house would probably sit at the committee and make amendments to the bill together. At the report stage, the committee chairman reports the bill, and further amendments to it would be made. The third reading (final stage) is merely a formality, where very few changes would take place.
As some bills are passed through the House of Commons, and others are passed through the House of Lords, both houses have to agree on the wording of the bill. This is achieved through a process called the Exchange of Messages. Exchanges of ideas between the two houses may happen many times, known as ping ponging, until an agreement is reached. But if the House of Commons refuses to accept the House of Lords version (agreed by a voting system), the House of Lords will be asked to accept the House of Commons version. If it does not accept, then the House of Commons may bypass the House of Lords by using the Parliament Acts 1911 and 1949.
All bills then require approval from the monarch. This final stage is known as the royal assent. Here, the bill can become an act and then pass into law.