When Joan Baldoví heads into parliament on Thursday to vote on Spain's new transparency bill he, like most politicians, will claim to have the thoughts and needs of his constituents at the forefront of his mind.

But Baldoví will know better than most what his voters actually want, thanks to a radical experiment in direct democracy.

Baldoví, an MP with the Spanish green party Compromís-Equo, has asked voters to sign up to an online platform that allows them to tell him what they think about the new law, and has promised to vote according to the majority opinion.

Baldoví says the idea dawned on him during an online discussion with a group of young voters.

"[They] asked if they could vote on my behalf," he said. "We thought about it afterwards and decided to try it with the transparency bill."

The new legislation has come to symbolise many of the problems the Spanish public has with its political system. Spain is one of the least open governments in the developed world, and one of only three in Europe, along with Cyprus and Luxembourg, to lack proper freedom of information laws.

The governing rightwing People's party has been beset by corruption scandals, including alleged illegal payments to its most senior leaders. The transparency bill is seen as an attempt to offset the political damage these have caused.

First mooted in 2004 under the previous, leftwing PSOE government, the bill fails to go far enough, its critics say, in its aim to tighten regulation of politicians' and public employees' tax declarations, financial assets and private activities.

Baldoví – who once stripped off his shirt and tie in a debate over banking, and clearly sees himself as a man of the people – hopes Thursday's political experiment will "open the voters' eyes to another way of practising democracy, and bring them closer to their politicians".

He said: "We want them to share in the democratic process and return the vote that they gave to us back to them. Voting does not have to be something you do only every four years."

The online direct democracy platform has been designed by the developers behind Agora Voting, a free software project designed to encourage open government. Once you have proved your identity by scanning in a copy of your national identity card you can vote on various elements of the proposed bill.

Baldoví said 2,000 people had taken part, as of midday on Wednesday, but he expected the final number of participants to be much larger.

As Baldoví's party is not in government, his vote is unlikely to change the course of the transparency bill. But, according to Antoni Gutiérrez-Rubí, a political analyst and professor of communications at the University of Navarra, the concept deserves attention.

"It responds to the need to offer new forms of citizen participation at a time of a profound breakdown in the confidence in political institutions," he said.

Victoria Anderica, of the freedom of information campaigning group Access Info Europe, also believes there is much to be learned from Baldoví's initiative. "Using it with the transparency bill was a very smart move because people know the subject," she said. "There has been a lot of political debate around it since it was first introduced, so people understand the various arguments."