The regulations state that there shall be two ordinary opponents. If opponents come forward ex auditorio, they must be given the floor before the second ordinary opponent. Thus the second ordinary opponent always speaks last.
The disputation normally begins at 10.15. There are no formal rules on how long the disputation can or must last. However, the first opponent usually speaks for approximately 1½ hours, and preferably not more than 1¾ hours. In addition, the second opponent normally speaks for approximately an hour. After the first opponent has spoken there is usually a break of about 30 minutes. Any opponents ex auditorio will be asked to speak after the second opponent.
As a rule the first opponent starts by giving a short summary of the content of the thesis, the general findings and suchlike. The purpose of this review is first and foremost to enable the public to follow the ensuing discussion. This should refer purely to the content of the thesis. Since it is the discussion between the opponent and the PhD candidate that is the first consideration, this introduction should be short and should not last more than 15 to 20 minutes. It may be appropriate to end the review by asking the PhD candidate if he/she has any comments. This gives the candidate the opportunity to correct any misunderstandings or errors that he/she has become aware of, and to give supplementary information about later developments etc.
The opponent follows with a critical scrutiny of the thesis. This should apply both to the general arrangement (outline, scope, organization, choice of material) and to methodology issues and the approach to individual questions. The opponent decides what questions are to be discussed. The scrutiny takes the form of a dialogue between the opponent and the doctoral candidate. Out of consideration for both the doctoral candidate and the public it is important that the doctoral candidate is given the opportunity to speak at an early stage. The first opponent usually rounds off his/her opposition with a general characterization of the work, but it may also be natural for the opponent to do this at an earlier stage.
The same applies to the second opponent, apart from the introduction to the content of the thesis. It is expedient that the two opponents agree on the distribution of roles in advance. For example, they may focus on different part of the thesis whereby one (usually the first opponent) concentrates primarily on general questions about the outline and methodology, while the other addresses more specific issues or other aspects. Previously it was common that the second opponent had particular responsibility for technical matters such as linguistic form, use of footnotes, printing errors etc. There is no longer any such rule, but it is natural that one of the opponents also takes up such questions briefly.
There is a tradition that the doctoral candidate and the opponent address each other in the third person (“the opponent”, “the doctoral candidate”), but this is not always fully implemented in practice.
The disputation ends by the Dean asking the doctoral candidate whether he/she has anything to add. Afterwards the Dean declares the ceremony to be over and announces that a report will be submitted to the University Board.