When is a photo a protest and a piece of cardboard a threat? Social worker and civil rights advocate Jolovan Wham will find out as he is now under formal police investigation over a photo of him holding a smiley face in public.

Wham said Wednesday that he has been ordered to report to Tanglin police, around two months after he took the photo in a show of solidarity with two youths under separate probes for photos they took of themselves demanding climate action.

�About 2 months ago, I held up a placard at Toa Payoh Central, took this picture and left immediately after. I�ve now received a letter that I�ve violated the Public Order Act and will have to be at Tanglin police division this Sunday at 2pm,� Wham wrote on Twitter.

�I did it in response to someone in sg who got investigated by the police for participating in a climate strike,� he added in another tweet today.

In response to Coconuts Singapore�s inquiries, the police said they were unable to comment further on the matter as it is the subject of an ongoing investigation.

On March 28, Wham posted a photo of himself with the smiley face online. It was taken outside the Toa Payoh Central Community Club, around the same spot where one of the climate activists had taken a photo.

It is illegal to hold public demonstrations without a permit in Singapore, even if it is just a silent protest involving one person. And the only public place Singaporeans have been granted a permit to do so is the Speaker�s Corner in Hong Lim Park.

Police said in April that they were investigating a 20-year-old man and an 18-year-old woman under the Public Order Act after photos of them posing in public with signs calling for climate action were posted online.

They were said to be founders of �fridays4futuresg,� a name that appears to be borrowed from a similarly named campaign by famed Swedish environment activist Greta Thunberg.

If convicted for his act of postmodern civil disobedience, Wham faces a S$3,000 fine.

In 2018, artist Seelan Palay was jailed two weeks after refusing to pay a fine after being convicted of an unlawful procession. He had walked from Hong Lim Park to the Parliament House while holding a mirror.