This afternoon's press conference in a Dublin solicitors office represents merely the latest chapter in the unusual relationship between Michelle de Bruin and those who police her sport.

Following a test conducted on the swimmer last January while out of competition in Ireland, a letter was sent from the Lausanne offices of FINA (the world swimming body) to the Irish Amateur Swimming Association last week. The swimmer was made aware of the contents at the weekend.

If de Bruin is found to have submitted a positive or manipulated test she could incur a ban of up to four years. De Bruin is now 28 and such a measure could effectively end her career.

Peter Lennon, the Dublin solicitor who represents De Bruin, stressed last night the nature of the difference of opinion between the swimmer and the testers.

"She had not failed a drugs test within the meaning of the rules." Expanding he commented: "Have you ever known an athlete to be suspended for taking a drug that is not itemised or particularised? Have you ever known an athlete to be suspended for interfering with a sample as alleged here?"

Whatever the outcome the matter represents at the very least another difficulty in a career which improved dramatically in late 1993 when Erik de Bruin, a former Dutch discus thrower, undertook to supervise Michelle de Bruin's training regime.

The breakthrough came at the European Championships in Vienna in 1995 when De Bruin won gold medals in the 200 metre butterfly and 200 metre individual medley.

The couple brushed with the authorities almost immediately when Erik de Bruin who (as a drug banned athlete) had been denied accreditation to the championships, gained access to the sensitive doping control area.

Officials became suspicious when De Bruin, bearing the accreditation of a Belgian coach, began writing out objections to the testing procedure in Dutch.

The chairman of the FINA doping commission, Mr Harm Beyer, a Hamburg magistrate threatened the couple with expulsion from the championships and only a day of intense negotiation by Irish officials saved the day.

Last year De Bruin was officially warned by FINA having missed two random drug tests. FINA rules allow for the suspension of a swimmer who misses three random drug tests within three years.

The sport has evolved a well-defined series of procedures for testing athletes. Samples once taken are entered into a secure chain of transportation and analysis. Increasingly in recent times the emphasis in testing procedures has been on random unannounced tests.

For testing purposes a sterile, disposable plastic beaker, is used to catch a midstream urine sample from the athlete. The athlete picks his or her own vessel for voiding and breaks the plastic seal on it. After that the sample is presented to the test officials who in the presence of the athlete split the sample into two portions, which will then be distributed further into two sterile specimen bottles. The athlete must be observed at all times during this procedure.

The bottles for the A and B specimens are once again selected by the athlete. They should be clearly marked and indentified.

Both the A and B samples are then sealed within separate zipper locked transport cases, along with verification forms. Special Envopak cases are used to prevent sample tampering. They enclose and protect the samples.

The cases are locked and coded. Non-repeating seals are placed on them. Both samples are placed in a transport case and not examined further till the samples are in the lab for testing. The athlete must sign verification forms attesting that there was no irregularity in the collection process. Any irregularities must be recorded at that time.

At the laboratory only the A sample is tested. Both the A and B samples remain in a refrigerated file to be used and compared in the event of disputes.

If there is a positive test the sample will be verified at least one more time from the A sample. The sealed B sample must remain untouched and on file. If an athlete wishes to dispute the results he may at his or her expense have the B sample tested while present, or request that such a test be carried out at another laboratory .

It is not yet known whether the B sample in De Bruin's case has been analysed or if the swimmer has requested such a measure to be taken.

The swimming world has been shaken in recent years by a series of scandals and suspensions involving high profile swimmers.

In 1995 a 15-year-old American swimmer, Michelle Fosse, tested positive for drugs and as recently as January of this year a Chinese swimming official was detained at an Australian airport attempting to import Human Growth Hormone, on his way to the World Championships in Perth.