A Thai court has convicted a prominent political activist of defaming the country’s monarchy and sentenced her to a two-year suspended jail term under a controversial law that criminalises any perceived criticism of the royal institution.

Patsaravalee Tanakitvibulpon, better known by her nickname Mind, had pleaded not guilty to an offence under Article 112 of the criminal code, relating to a speech she gave at a rally in the capital in March 2021.

A judge at the Bangkok South Criminal Court officially sentenced her to three years in prison for the crime known as lese majeste, but reduced it to a two-year suspended term due to her co-operation.

She was acquitted of a charge of violating an emergency decree on public gatherings because she was not an organiser of the event.

A small group of supporters handed flowers to the 28-year-old before she entered the court.

“I am confident that the content of my speech on that day was polite and humble. I spoke with good intentions, not defamation. It was necessary to talk about the monarchy and Thai politics because it had become an issue,” she told reporters.

Patsaravalee was one of a new wave of leaders who took a prominent role in the series of unprecedented protests that shook Thailand beginning in 2020, calling for reforms in the monarchy.

The institution is traditionally deeply revered and is protected from criticism by the lese majeste law, which imposes severe penalties on those found to violate it, including up to 15 years in jail per offence.

But agitation for a more liberal atmosphere surrounding discussion of the subject has grown since the death of King Bhumibol in 2016 and the accession of his son, King Maha Vajiralongkorn.

The conviction came on the same day that Thailand’s Constitutional Court is set to hand down its verdict in a case against the political party that won most seats in last year’s election over its campaign call to amend Article 112.

The charge was that its platform was tantamount to calling for the overthrow of the system of constitutional monarchy.

If the Move Forward party loses the case it may be told to cease its push for reform.

A loss may also leave it vulnerable to further action, including a move for its dissolution.