Ambush marketing occurs when a company affiliates itself with a major event without paying the requisite sponsorship fee. One of the aims of this thesis is to discuss whether the phenomenon can be deemed to be unethical or good business practice. This will be done through exploration of current academic literature, consumer opinions and ethical ideologies. With that in mind, the principle aim of this thesis is to discuss whether the London Olympic Games and Paralympic Games Act 2006 (London Act) is a proportionate response to the threat of ambush marketing. The discussion of proportionality examines whether the Act has struck the correct balance between all of the key stakeholders and will assess whether any elements of the Act are arguably disproportionate. The empirical findings of this research also highlight that traditional trademark law and the law of passing off are limited considerably in their ability to protect major sporting events from the threat of ambush marketing. As a result of this, it is argued that the London Act is a well-balanced and proportionate response to the threat of ambush marketing.