Tony Blair has exposed himself to the committee spotlight
A select committee could meet for a one off evidence session but usually their inquiries take a longer and more detailed approach.
They can choose any issue to look at within the area of work of the relevant department and will then seek written and oral evidence.
Key witnesses usually give oral evidence in a public session but sensitive evidence is taken in private.
Government ministers normally give evidence at some stage but pressure groups, professors and experts are also given a say.
Select Committees have the power to send for "persons, papers and records". But there are some people they are not able to call to account.
Members of Parliament only attend voluntarily and the government has faced criticism from some select committee chairman for refusing to allow special advisers before committees.
The Transport Committee even accused the prime minister of refusing to allow Lord Birt appear before them because "his performance would be an embarrassment".
A committee inquiry may also include study visits at home and abroad and meetings away from Westminster.
After all the evidence has been taken - sometimes a long process - the committee begins work on its report. Members discuss and draft the report which is, generally, unanimous.
When strong differences of opinion do exist members can vote on amendments to the report.
The publication of a select committee report is often a major news event and may elicit a government response very quickly.
When the Home Affairs Committee published its report on drugs the then Home Secretary David Blunkett rebuffed calls to downgrade Ecstacy to a class B drug the day the report was released.
Government departments are expected to reply to committee reports within 60 days and there is a chance that the report will be debated on the floor of the house.
Since 1997 select committees have also had a role in considering draft bills.
The prime minister has stated that the government is looking to expand pre-legislative scrutiny.
Select committees have become central to the reform of Parliament and their importance was again strengthened by the announcement in April 2002 that the prime minister would submit himself to the biannual scrutiny of the Liaison Committee.
Tony Blair's first session before the committee, made up of select committee chairmen, came in July 2002.
The meeting allowed members to quiz the PM on such topics as cabinet government, school spending and Iraq.
The session was seen by many as a landmark in prime ministerial accountability.