'It's a voluntary system so it has to depend on the levels of interest among members of the public,' a judiciary spokeswoman said.

The tribunal, jointly run by the judiciary and the Commerce and Economic Development Bureau, is tasked with rating print publications, videos and films. Unlike jurors in court, who are enlisted, adjudicators for the tribunal are volunteers.

But volunteers say one reason for the lack of interest is the fact that much of their work is dull - despite what wags might say about being paid to watch pornography.

Amy Yuen Siu-man has served on the tribunal for seven years. She sits twice a year for between half a day and a day, either to scan print publications or watch 20 to 30 blue movies.

'Contrary to the public impression that our job is full of controversial issues, it's actually very boring,' she said. 'There is always a lot of repetition in the content.'

But her frustration stems mainly from what she describes as the tribunal's 'systematic imperfection'.

The presiding magistrate starts each session by repeating the same set of legal principles.

'[But] there are actually no clear principles telling us when to make what decisions,' Yuen said. 'The ultimate decisions could be reached purely personally. This is arbitrary.'

The tribunal has been no stranger to controversy since its creation in 1987.

In 2007, the Court of First Instance overruled a tribunal decision which banned a publication by the Chinese University Student Press containing questions about fantasies of bestiality and incest.

In 1994, a picture of Michelangelo's famous statue David in an advert was ruled unsuitable for children.

The tribunal proposed enlarging its pool of adjudicators in an apparent effort to increase its credibility with the public after the government pledged to overhaul the system. It also introduced a limit on how long adjudicators can serve for, limiting their term to nine years. But Civic Party lawmaker Audrey Eu Yuet-mee said this was still too long.

'I was very surprised when I checked the law which says nothing about 'experience' [as a criteria for adjudicators]. So why does the judiciary keep appointing the same people?' she said.

The Labour Party's Cyd Ho Sau-lan believes their tenure should be shortened to six years, in line with appointments to other bodies.

But while Eu supported expanding the pool, long-time adjudicator Yip Hing-kwok objected, saying it would lower the quality of judgment.

The district councillor has been on the job for more than a decade.

'It's meaningless if you have too big a pool; the quality of adjudicators would vary a lot,' he said.

The judiciary said a larger pool was needed because of 'a regular and healthy turnover of adjudicators, and ... better continuity of membership'.

As for Yuen, she said she would press on because it was her civic duty. But occasionally, even after all she has seen, something surprisingly appealing occasionally catches her eye.

'It was so surprising to me when I saw some Taiwanese magazines intended for gay men; they had superb pictures ... blue sky and turquoise water,' she said.

This showed how Taiwan's pornographic culture differs from that of Hong Kong, where erotic goods are boring and lack class, she said.

Even so, she said, explicit sex rather than aesthetic values were the key factor when deciding a classification.