This trademark survived a challenge last year by a British Company who argued that the shape of the figures was too functional to be protected in such a way. The decision was a big-win for Lego as trademarks, providing they are being used, may be renewed without any time limitation, meaning that Lego essentially have a monopoly on the figures for as long as they choose to. It follows an earlier decision by the European Court of Justice in which Lego lost the trademark for its iconic brick as it was decided the design pertained more to functionality than branding. The two starkly different outcomes in these highly similar cases demonstrate how finely the line is drawn between what constitutes a trademark and what does not.
If you’re interested in reading more about Lego’s recent trademark case, check out this informative Guardian article on the topic here: http://www.theguardian.com/lifeandstyle/2015/jun/16/lego-trademark-protection-mini-figures-european-court-justice-best-lock