The law garnered attention following the failed Catalan independence bid of October 2017, when Spain rounded up those involved in organising a banned referendum and charged them with a string of offences — including sedition.
In an interview with La Sexta television, Sánchez said his Socialist party and Podemos, its hard-left coalition ally, would present the initiative to parliament on Friday in a move that would “defuse” tensions in Catalonia.
“We are going to present a legislative initiative to reform the crime of sedition and replace it with an offence comparable to what they have in other European democracies such as Germany, France, Italy, Belgium and Switzerland,” he said.
The move would be “a step forward”, he said, revising a crime dating back to 1822.
“I think it will be an initiative that will also help to defuse the situation in Catalonia,” Sánchez added.
Sedition would be renamed an “aggravated public disorder”, with penalties similar to those “set out in the penal codes of European democracies”.
Separatists in the wealthy northeastern region have long clamoured for independence from Spain, but remain deeply divided over how to achieve it.
The failed independence bid sparked Spain’s worst political crisis in decades, with then-Catalan leader Carles Puigdemont and several others fleeing abroad to escape prosecution.
However, a dozen people were put on trial, and nine were convicted of sedition among other charges and sentenced to heavy jail terms. They were later pardoned.
Spain still wants to try Puigdemont and two others, and the proposed bill would not change that, Sánchez said.
“The crimes committed in 2017 will continue to be present in our penal code, although no longer as crimes of sedition… but as a new type of crime called aggravated public disorder,” he said.