BANGKOK — Thailand’s most dynamic political force in years was ordered disbanded on Friday by the country’s Constitutional Court, in a ruling that rights groups say is part of a pattern of judicial harassment aimed at smothering democracy.

The Future Forward Party was found to have violated a law governing political parties by accepting a loan from its young tycoon leader, Thanathorn Juangroongruangkit, to fund an electoral campaign.

The party maintains that the 191 million baht loan, equivalent to about $6 million, was legitimate, and that the campaign financing rules are so ambiguous that it would have been impossible to know whether the loan contravened them. Other political parties have taken out loans without any legal ramifications.

For a country where the same politicians and army generals have dominated politics for decades, the Future Forward Party offered something fresh.