版權律師Liz Ward是Virtuoso Legal的創始人，他說Guess "似乎是通過第三方，即Brandalised，合法地獲得了班克斯的藝術作品，他們說他們有權利將班克斯的藝術作品商業化並用於商品上"。
He wrote on Instagram: "They've helped themselves to my artwork without asking, how can it be wrong for you to do the same to their clothes?"
After the artist posted his message encouraging shoplifting, a criminal offence, Guess closed the store to the public, placed security outside and covered up the window display. Staff in the shop declined to speak to the BBC.
Copyright lawyer Liz Ward, founder of Virtuoso Legal, said Guess "appear to have legitimately sourced the Banksy artwork via a third party, namely Brandalised, who say they have rights to commercialise and use Banksy's artwork on goods".
She said: "It isn't known if Banksy approved or even knew about this deal. If he did know about it, then perhaps his comments are there to create some kind of guerrilla marketing campaign. If he didn't know about it, then he must be quite annoyed, especially as such mainstream companies and brands don't accord with his anti-establishment views.
'Not right to encourage shoplifting'
"The short point is that Banksy should be pursing Brandalised and or Guess for infringement of his work. However, given she/he wants to remain anonymous, that may well be impossible."
Earlier this week, Banksy won an appeal to allow him to keep the trademark of one of his most famous images, a money wearing a sandwich board, at the EU Intellectual Property Office.