While there are exceptions, there are generally four evidence sessions. Oral evidence may be requested by the committee or written evidence submitted by interested parties on their own initiative. Most evidence-taking sessions have been held in the Boothroyd or Grimond Rooms in Portcullis House - these rooms are the only ones large enough for all the members of a Public Bill Committee to sit in a horseshoe formation.
Once the evidence taking is completed, the traditional practices of 'Standing Committees' are reverted to. Members face each other as in the main chamber, and the bill is considered clause by clause.