HKU Law and Technology Centre launches HKU AI Lawyer: Sentencing Predictor for Drug Trafficking

HKU Law and Technology Centre launches HKU AI Lawyer: Sentencing Predictor for Drug Trafficking

Recent advances in artificial intelligence (AI) and machine learning have great potentials to bring revolutionary changes to legal practice. AI can be used to draw insights from past judicial decisions to predict future outcomes. In the criminal justice system, one essential aspect is sentencing. Much attention has been placed on how AI informs decisions about sentencing and how to use AI to assist people to obtain and make use of sentencing information.

The HKU’s research team led by Professor Ben Kao of the Department of Computer Science and Professor Anne Cheung of the Faculty of Law has developed a Stage-1 model of HKU AI Lawyer – an AI-assisted sentencing predictor for the offence of trafficking in dangerous drugs in Hong Kong.

The sentencing predictor is capable of handling 8 types of commonly used dangerous drugs. Users only need to provide relevant information through responding to four simple questions, and the predictor will generate an estimated term of imprisonment with an explanation of the effect of individual selected features on the overall predicted sentence. Another useful feature of the predictor is that it will at the same time show the links to court decisions which are relevant to the given facts.

A workshop was held on Tuesday, May 18, 2021, to introduce the HKU AI Lawyer and demonstrate its use. Mr. Wilson Chan, Deputy Director of the Hong Kong Federation of Youth Groups, also shared how his organization benefits from the sentencing predictor.

The sentencing predictor is a pragmatic tool for professionals including lawyers, social workers and teachers to access relevant sentencing information of drug trafficking much quicker, thereby reducing their research time and cost. It also serves to inform the public of the likely legal consequences of committing drug trafficking offences.

The predictor is based on an innovative combination of legal domain knowledge and AI technologies. To make sentence predictions, the machine is trained to master two kinds of knowledge. The first kind includes the legal principles, sentencing guidelines, logical steps, and the salient factors that judges generally follow in determining sentence. For example, based on the types and weights of the drugs involved in case, a judge would first determine a starting point of the sentence. The sentence is then adjusted based on relevant aggravating and mitigating factors. The machine was taught the domain knowledge by legal experts. The second kind of knowledge is statistical rules derived from historical judgments. Computer science experts use machine learning and natural language processing techniques to train the machine so that it possesses the intelligence to read and comprehend previous court judgments. With references to more than 3,000 court judgments, the machine remembers and understands the relevant sentencing logic of the historical cases. This allows the machine to derive statistical rules on the quantitative elements when given a new case for which prediction is to be made, for example, given an aggravating factor, such as cross-border trafficking, the number of months of additional imprisonment that would likely be imposed.

In the next phase, subject to the availability of resources, the research team will apply AI technologies in other legal domains, including developing a personal injuries compensation predictor.

The sentencing predictor is available at https://clic.org.hk/app/sentencingpredictor.

香港大學法律與科技研究中心推出「港大人工智能律師:販毒罪量刑估算程式」

人工智能和機器學習近年發展迅速,其巨大潛力可能會令法律實務產生革命性的改變。人工智能可從過往的司法裁決中發掘新知,預測類似案件的結果。刑事司法制度中,量刑是重要的一環。如何用人工智能為量刑提供參考信息、如何讓人工智能幫助公眾獲取和使用量刑資料,都是廣受關注的課題。

香港大學計算機科學系高志明教授和法律學院張善喻教授率領研究團隊,研發出「港大人工智能律師」的第一階段模型,即人工智能輔助估算量刑程式。本程式旨在估算香港販運危險藥物的量刑。

該量刑估算程式涵蓋8種常用的危險藥物。程式用戶只需回答四條簡單的問題,程式便可以獲取相關資料,從而估算出監禁刑期,並解釋各個選定的特徵對整個刑期的估算有何影響。程式還有另一實用功能,可針對用戶描述的案情,提供最密切相關的法院案例的連結。

研究團隊於2021年5月18日(星期二)舉辦了工作坊,介紹「港大人工智能律師」的背景並示範如何使用量刑估算程式。香港青年協會副總幹事陳文浩先生亦分享了他所在的服務機構如何從此程式中受惠。

量刑估算程式是律師、社工和教師等專業人士的實用工具,能幫助他們更快捷地獲得販毒的量刑資料,減少研究時間和成本。程式亦可幫助公眾了解觸犯販毒罪可能引致的法律後果。

量刑估算程式開創性地結合了法律領域知識和人工智能技術。機器能夠透過訓練掌握兩類知識以估算刑期。第一類知識為法律領域知識,包括法律原則、量刑指引、邏輯步驟以及法官在量刑時通常考慮的重要因素。例如,法官會根據案件中的毒品種類和重量首先決定量刑的起點,然後再考慮各種加刑和減刑因素來調整刑期。法律專家訓練機器學會領域知識。第二類知識是從以往的判決中獲得的量化數據。計算機科學專家利用機器學習和自然語言處理技術來訓練機器,使其具有智慧去讀取和理解以往法院的判決。通過參考3,000多個法院判案書,機器可以記住並理解與以往案例相關的量刑邏輯。當要對某個案件進行估算時,機器能夠運用這些知識得出有關量化要素的統計規則。例如,當案件具備如跨境販毒一類的加刑因素時,程式就會估算出額外的監禁月數。

在資源許可的情況下,研究團隊將在下一階段把人工智能技術應用到其他法律領域上,包括研發有關人身傷害賠償的估算程式。

販毒罪量刑估算程式的網址是:https://clic.org.hk/app/sentencingpredictor

HKU AI Lawyer: Sentencing Predictor for Drug Trafficking desktop version
「港大人工智能律師:販毒罪量刑估算程式」桌面版

 

HKU AI Lawyer: Sentencing Predictor for Drug Trafficking mobile version
「港大人工智能律師:販毒罪量刑估算程式」手機版

 

Professor Anne Cheung, HKU Faculty of Law (First Left), Professor Ben Kao, HKU Department of Computer Science (Middle) and Mr. Michael Cheung, HKU Faculty of Law (First Right) presented the HKU AI Lawyer: Sentencing Predictor for Drug Trafficking.
香港大學法律學院張善喻教授 (左一) 、香港大學計算機科學系高志明教授 (中) 及香港大學法律學院張文傑先生 (右一) 介紹及示範「港大人工智能律師:販毒罪量刑估算程式」。

 

Mr. Wilson Chan, Deputy Director of the Hong Kong Federation of Youth Groups (First Left), Professor Anne Cheung, HKU Faculty of Law (Second Left), Professor Ben Kao, HKU Department of Computer Science (Second Right), Mr. Michael Cheung, HKU Faculty of Law (First Right).
香港青年協會副總幹事陳文浩先生 (左一) 、香港大學法律學院張善喻教授 (左二) 、香港大學計算機科學系高志明教授 (右二) 、香港大學法律學院張文傑先生 (右一)。

 

Members of the research team and Mr. Wilson Chan, Deputy Director of the Hong Kong Federation of Youth Groups (Fourth Right).
香港大學研究團隊成員及香港青年協會副總幹事陳文浩先生 (右四)。