Kurtis had originally recorded Duff’s refusal to give her name as the reason for the search, which is not sufficient legal grounds.
It sounds like jobsworth police who don't know the law to me and just want to exercise their power against anyone who they take an exception to.
But in a motion to have the case thrown out, Nicholas Yeo, representing Howard, argued that the search was justified by Duff’s refusal to cooperate. Her behaviour had given officers reason to fear that she had mental health problems, while her refusal to give her identity meant no search could be made on the police national computer to assess whether she posed a risk.
...so lets change the story in court to her being mentally unstable to justify the illegal search.
I bet the arrest for assault/obstruction were little more than her handing the guy the card against their wishes as well. The police attract people who like power and when people exercise their right to stay silent and don't comply with demands it no doubt winds them up so it becomes a case of "I wonder what offences can we throw at them?".