In a perfect world, pluralistic legislatures such as ours would be models of calm, rational debate. In the real world, they are only human and thus flawed. As a result, they are subject to codes of conduct that draw the line between free speech and behaviour or language deemed objectionable. The latter can still be quite colourful or clever, even if ruled out of order by the presiding officer. That is hardly true, however, of words like slave, spastic and running dog when used as personal insults, as they were last week by lawmakers of the League of Social Democrats to constitutional affairs minister Stephen Lam Sui-lung. Chief Secretary Henry Tang Ying-yen took the unusual step of complaining about the treatment of Mr Lam. Legco president Tsang Yok-sing, who finally ejected the lawmakers when they ignored his call for order, replied that he had a duty to ensure freedom of speech. After voters elected the LSD's provocative commentator-turned-politician Wong Yuk-man, many predicted more fireworks in the Legco chamber. Retired president Rita Fan Hsu Lai-tai disagreed: 'Yuk-man is loud ... but being loud does not mean what he says is reasonable or unreasonable.' New president Mr Tsang said it was inevitable that lawmakers would use radical words and brandish unusual 'props' to attract attention. He also said Mr Wong's banana-throwing gesture during Chief Executive Donald Tsang Yam-kuen's policy address last October would not become a trend. After his election, Mr Wong said LSD lawmakers were not there to disrupt but to 'reflect people's views and better supervise the government'. Having said that, they would do well to remember that personal attacks may not endear them to middle-class voters known for political moderation. While there is a place in the legislature for the unexpected and the unconventional, we would like to repeat what we said after the 'banana throwing' incident - there is no place in our system for the hurling of abuse or throwing of fruit in the Legislative Council chamber. Abuse of free speech must not be allowed to disrupt rational debate. Mr Wong and his colleagues can be loud, but not abusive.