The Tonga Legislative Assembly has enacted law allowing for 17 MPs to be popularly elected, with nine to be chosen from among the noble families.
This means that democratically elected MPs will have a majority in Parliament for the first time following the next elections, due in November.
The Parliament is still to decide the boundaries for the 17 seats but our correspondent says this is likely to be resolved by Tuesday next week when the MPs are due to rise.
Other law changes enacted today include the registration fee for candidates rising to just over 200 US dollars instead of the 500 dollars the Government had been promoting.
And limits on campaign funding, which were going to be lifted substantially, have been kept at just over five thousand US dollars after a plea from the pro-democracy MPs.