许其昌大律师于2008年加入德辅大律师事务所。许大律师拥有广泛的执业经验，他的执业范围涉及德辅大律师事务所的各个主要业务领域，包括行政及宪法、商法及公司法。他曾为一系列的商业事宜提供咨询意见，包括广播、电讯、金融与证券、保险、船舶、民事欺诈、法律冲突与法律管辖权等。
许大律师在其牛津大学法学硕士的竞争法课程中成绩优异。他正积极地在香港开展竞争法的执业。在2015年，许大律师代表香港通讯事务管理局（协助伦敦 Brick Court 大律师事务所的 Mark Hoskins 御用大律师以及张健利资深大律师事务所的陈文敏资深大律师）参与司法复核，林云浩法官颁布此案判决书 Television Broadcasts Limited v Communications Authority & The Chief Executive in Council [2016] 2 HKLRD 41，此案为香港竞争法基本原则及例如举证责任等的重要问题奠下重要基础。在2016年1月，许大律师被任命为香港 竞争事务委员会外部法律顾问。在2016年10月，他被香港大律师公会推荐至伦敦以竞争法闻名 的Brick Court大律师事务所实习竞争法。
许大律师参与过许多著名的案件，例如霸王诽谤案，有关电视广播行业的一系列司法复核案件以及在一宗高价值的资产冻结令申请中成功冻结了价值超过3.35亿欧元的资产。
除了法庭诉讼外，许大律师也经常依照香港国际仲裁中心及联合国国际贸易法委员会规则参与国际仲裁。
德辅大律师事务所的许其昌大律师在受访者中因其在广泛的各个领域中均衡的表现而广受赞誉，例如在竞争、诽谤和清盘等领域。受访者进一步指出许大律师是一位“很容易相处且友好”的大律师，并“正处在其上升的道路上”，且已经发展了一个稳定的客户群体。
《钱伯斯指南（亚太）》(2020)
德辅大律师事务所的许其昌大律师执业领域非常广泛。他在清盘、董事责任以及竞争法事宜的执业经验丰富，并且善于处理金融服务、证券以及电讯广播领域的事宜。事务律师们对于他总能提出『新颖的解决方法』而印象深刻，一位评论者认为他不仅能够在『证据杂乱』的情况下解决问题，并且还能够『非常有效地向客户阐明他聪明的想法』。同业者称赞许大律师『谨慎而实际』的诉讼技巧以及其在法庭中『迅敏的反应速度』。
《钱伯斯指南（亚太）》(2019)
Administrative and Public Law:
- Television Broadcasts Limited v The Communications Authority & The Chief Executive in Council HCAL 176/2013 (CFI) (Junior Counsel for Communications Authority) – Judicial review concerning (i) whether a finding of breach of the competition provisions in the Broadcasting Ordinance engages Articles 10 and 11 of the Hong Kong Bill of Rights, and (ii) the Communications Authority’s substantive findings on competition law issues.
- Asia Television Limited v Communications Authority FAMV 23/2013 (CFA), [2013] 3 HKLRD 618 (CA), HCAL 77/2012 (CFI) (Junior Counsel for Communications Authority) – successfully defended a judicial review against the Communications Authority in relation to a report publishing its investigation against the Applicant. The Court of Appeal’s judgment in [2013] 2 HKLRD 354 is the leading authority on hearing in camera.
- Asia Television Limited v Chief Executive in Council [2012] 3 HKLRD 1 (CFI) (Junior Counsel for the Interested Party) – Leave application concerning the recommendation for granting new television licenses.
- Sanyuan Group Limited v The Stock Exchange of Hong Kong Limited FAMV 52/2009 (CFA),[2009] 5 HKC 124 (CA), [2008] 4 HKC 367 (CFI) (Junior Counsel for the Hong Kong Stock Exchange) – successfully defended a judicial review against the Stock Exchange's decision to delist a company listed on the main board.
- Hong Kong Aircrew Officers Association v The Director-General of Civil Aviation HCAL 96/2008 (CFI) (Junior Counsel for the Applicant) – judicial review against the Director-General for allowing a dispensation of the three-pilot requirement for a long haul flight
Company and Corporate Insolvency:
- Re Anxin-China Holdings Limited HCCW 317/2015, Re China Solar Energy Holdings Limited HCCW 108/2015, Re K Vision International Investment (H.K.) Limited HCCW 282/2011, Re Unisign Limited HCCW 325/2010 Re Silver Yield Industries Limited HCCW 353/2009, Re CASSIS Limited HCCW 560/2008 – Applications for appointment of provisional liquidators
- Re China Fishery Group Limited – acted as expert in Hong Kong law in provisional liquidators proceedings in the Cayman Islands
- Re Ruifeng Petroleum Chemical Holdings Limited HCCW 280/2013, Re First Natural Foods Holdings Limited HCMP 350/2012 – Schemes of arrangement for insolvent listed companies
- Re Dong Yick Chemical Company Limited HCCW 60/2015, Re Polywell Pacific Limited HCMP 440/2015, Re Jing Jin Travelling Bags Manufactory Limited HCCW 359/2011, Re Globe Industrial Technology Company Limited HCMP 189/2011, Re 2I Dental Centre Limited HCMP 712/2009 – Unfair prejudice / just and equitable winding-up petitions
- Re Win Star Toys Manufactory Limited HCMP 1403/2015, Re Hub Global Freight Solutions (HK) Limited HCMP 670/2012 – applications for disclosure of corporate books and records pursuant to section 740 of the Companies Ordinance
- Li Xiao Yun v China Gas Holdings Limited [2015] 5 HKLRD 845 (CA), HCCL 18/2011 (CFI) (Junior Counsel for the Defendant) – claim by former directors pursuant to the company’s share option scheme
- Re Grand Field Group Holdings Limited [2009] 5 HKLRD 105 (Junior Counsel for the Defendants) – leading authority on the proper purpose doctrine in directors’ exercise of power
- Re OASIS Growth Income Investments Limited HCCW 133/2008 (Junior Counsel for HK Aircraft Engineering Co Ltd) – claim in common law possessory lien over aircrafts
- Re Seamless Green China (Holdings) Limited HCA 2114/2009, HCA 2441/2009 – injunction against the voting rights of shares in a listed company
- Re Creative China Limited [2014] 1 HKLRD 1108 (CFI) – derivative action concerning a BVI company
Commercial, Financial and Regulatory Law:
- LIXIL Corporation v Cai Jianshe HCMP 1860/2015 – Mareva injunction under section 21M of the High Court Ordinance, freezing over €335 million worth of assets in Hong Kong
- Compania Sud Americana de Vapores S.A. v Hin-Pro International Logistics Limited [2015] 2 HKLRD 458 (CA), HCMP 1449/2014 (CFI) – Mareva injunction under section 21M of the High Court Ordinance in aid of an English legal action for breach of jurisdictional agreement, Mareva injunction against non-parties, appointment of interim receivers
- Dexia SA/NV v Epic Investments SA HCMP 1859/2013 – successfully discharged a Mareva injunction obtained pursuant to section 21M of the High Court Ordinance which sought to freeze over €62 million worth of assets
- Husqvarna AB (Publ) v Freyer Power Technology Limited HCA 529/2016,Labuan INS International Trust Limited v Achiever Shanghai Limited HCA 941/2014, Johann Young v Vermont Silicon Inc. HCA 1886/2012, Hextronik Limited v Sky RC Model Mfg. Limited HCA 1384/2012, Valetal Global Communications, Inc. v Chinacomm Ltd. HCA 1978/2011, Sino Resources Group Limited v Hung Chen Richael HCA 2477/2009 – Mareva injunction applications
- China Metal Recycling (Holdings) Limited v Chun Chi Wai & Others HCA 1412/2013 – represented one of the defendants in a claim over HK$1.2 billion commenced as a result of the SFC’s investigation of a listed company
- Basab Inc. v Superb Glory Holdings Limited HCA 6/2014 – represented the receivers appointed under a debenture in a claim for selling the security at an undervalue
- Re China Best Group Holding Limited HCMP 745/2013, Re First China Financial Network Holdings Limited HCMP 2502/2012 – directors’ disqualification proceedings under section 214 of the Securities and Futures Ordinance
- Fubon Bank (Hong Kong) Ltd v First Prime Group Ltd [2009] 4 HKLRD 283 – represented victims of international investment fraud, applied for a Mareva injunction over money held in a bank
- Ford Union Limited v National Australia Bank Limited HCA 1800/2009 (Junior Counsel for the Plaintiff) – claim for negligent financial advice
Other Notable Cases:
- Bawang International (Group) Holding Limited v Next Magazine Publishing Limited HCA 1109/2010 (Junior Counsel for the Plaintiffs) – Defamation claim of over RMB500 million in loss of business profits
- Super Worth International Limited v ICAC [2016] 1 HKLRD 281 (CA) HCMP1320/2012 (CFI) – leading Hong Kong authority on (i) the applicable law of legal professional privilege and (ii) whether legal professional privilege should be extended to accountants advising on tax law
- Wong Kam Fung v Smart Profit Enterprises Ltd [2014] 5 HKLRD 853 (CA), HCMP346/2014 (CFI) – Purchaser’s lien in conveyancing transactions
- Tullet Prebon (Hong Kong) Limited v Chan Yeung Fong Nick & Others HCA 2197/2009 (Junior Counsel for the Plaintiff) – represented an international brokerage group in a claim totalling over HK$10 million for wrongful termination of employment agreement and poaching of employees by competitors
- Tadjudin Sunny v Bank of America [2009] 4 HKLRD 662 (Junior Counsel for the Defendant) – represented the bank in a claim involving a novel issue of whether an anti-avoidance provision can be implied into an employment contract