Parliamentary immunity will be sharply curtailed if the constitution draft is endorsed in its present form.
In essence, MPs and senators will no longer have immunity from criminal proceedings during parliamentary sessions if they are charged with corruption or any offence that carries a jail term of 10 years or more.
In the past, even lawmakers accused of murder have managed to put off facing justice as long as parliament was in session.
Charter writers decided on Friday to add criminal offences with imprisonment of 10 years or more to the charges from which MP and senators cannot seek immunity during a meeting session, said Kamnoon Sidhisamarn, a spokesman for the Constitution Drafting Committee (CDC).
The previous revision of the charter added only corruption charges to the offences.
Under past constitutions, MPs and senators could be prosecuted during meeting sessions only for flagrant felonies or when their assemblies allowed it.
"In practice, however, both assemblies protected their members and never allowed them to be prosecuted," said Mr Kamnoon.
"They felt they had to maintain the dignity of parliament and argued that it was line with international practices."
Parliamentary immunity is granted in several countries to prevent lawmakers from being harassed or obstructed by the executive branch while they are deliberating laws.
Mr Kamnoon said the revised draft also allowed prosecution if the accused member agrees to it, without having to seek permission from his assembly.
As well, the charter drafters rewrote a clause to ensure that an assembly president cannot "order" the release of one of its members.
It replaced the word "order" with "request", allowing officials to refuse him if they have sound reasons.
An assembly may also allow a prosecution to proceed without calling a vote if the accused member asks for justice to be allowed to take its course.
"In the past, an accused member would proudly announce to the public that he stood ready to be prosecuted because either he really wanted to prove his innocence quickly, or he knew his assembly would never allow it," Mr Kamnoon said.
