When Suthep Thaugsuban promised two months ago to step up political campaigns against what he viewed as the government's hidden agenda and populist policies, he wasn't kidding.
His Democrat party has held weekly rallies in several provinces to tell the public "the truth" about what he believes are the government's missteps.
As ever, the Democrats claim former prime minister Thaksin Shinawatra is exerting his influence behind the government's every move.
Mr Suthep's bold assertion in an interview with this newspaper early this week that prime minister Yingluck Shinawatra will be driven out of the country and end up in exile just like her brother begs for a clearer explanation.
Mr Suthep claimed that, unless Ms Yingluck could shake off her brother's influence and stop protecting his and their family's interests, she would face a public backlash and would not be able to stay in the country.
There is no question that this is a strong assertion on the part of the former deputy prime minister. The problem with the remark is it could be read as a threat against the nation's popularly elected political leader. How would Ms Yingluck end up as in exile? Is Mr Suthep suggesting the return of a coup? Is he saying that mobs would overthrow the government?
Stipulate that every Thai citizen has the right to free speech. Stipulate further that Mr Suthep's comment on the prime minister did not call for immediate violence _ one of the few legal restraints on free speech. And concede even further that his comments did not defame Ms Yingluck.
Mr Suthep's speech met every legal test. It was his opinion, stated freely, not at all slanderous and resulting in no violence by his followers, either on the ground or later in the media.
Despite all of that, however, it is still decidedly fair and pertinent to question that outburst. It was not a direct, physical threat to the prime minister, or to the national institutions.
It was, however, a threat to manners, to the political process, and ultimately to our society and culture. There may be some debate over whether Thailand is still the Land of Smiles. That is not the same as saying it is a land of reviles.
There is still a clear line marking civil discussion in the country.
Lamentable, but true enough: speakers at rallies for the People's Alliance for Democracy and the United Front for Democracy against Dictatorship have often crossed the civility line. But none of them was a deputy prime minister, or the secretary-general of the country's oldest and one of the most respected political parties.
Mr Suthep suggested prime minister Yingluck could keep the public's confidence if she learns to become her own woman and governs the country with the nation's interests at heart, rather than as a nominee for her brother. That was a constructive suggestion. The accompanying threat of exile was unnecessary.
Ms Yingluck, Mr Suthep and any other politician are legitimate targets for criticism. That is all the more reason why they have an extra obligation to stress that political disagreements should be settled at the ballot box. Threats and near-slanderous attacks are unacceptable.