What offences declare a Senator incumbent?

Incumbent means senators that are still in office. There are some senators that are incumbent, but because of some offenses, they may be forced to vacate their seats. One of the common issues is they have already reached the maximum term of their services so they cannot run for the position anymore. There are different rules all over the world about this.

For instance, in one country, it may be okay for senators to run two consecutive terms, but in other countries, this may not be allowed. Those who are in the Senate who are also proven to have done things that are not allowed by the constitution may also be required to leave their positions for other potential senators.