Party conferences continued on Sunday, with government partners the Left Alliance calling for the decriminalisation of drug use.
In a statement approved by conference delegates, the party argued that drug abuse should be addressed through social and healthcare policies rather than through the judicial system.
The party said that the use and possession of small quantities of drugs should be decriminalised but that the manufacture, import, transport and sale of drugs should remain punishable by law.
The Left Alliance also wants to legalise the medical use of psychedelics.
Also at the party conference in Pori on Sunday, delegates approved a new Nato policy, in line with a proposal by the party board.
According to the new policy, Finland must emphasise that membership in Nato will be defensive, and that no nuclear weapons, permanent Nato military bases or forces will be allowed in the country.
A counter-motion demanding that Finland remain militarily non-aligned was voted down. The Left Alliance has traditionally been the most strongly opposed to Nato membership of Finland's main political parties.
NCP backs snus sales
Meanwhile the main opposition National Coalition Party (NCP), at its conference, approved an initiative to legalise the sale of snus, an oral tobacco product.
The proposal by the NCP student wing gained little support when it was last raised at a party convention two years ago.
"The snus trade involves a huge amount of organised crime. With legalisation, we can tackle the black market trade. At the same time, tax revenues will remain in Finland rather than flowing to a neighbouring country," said Nea Nättinen, chair of the NCP student wing.
Sweden has secured an exception to the EU's ban on the sale of snus. Large amounts of the product are sold at shops along the Swedish border and brought into Finland.
NCP delegates meeting in Kalajoki, Northern Ostrobothnia also re-elected MP Antti Häkkänen as the party's first deputy chair. MP Elina Valtonen and Tampere Mayor Anna-Kaisa Ikonen will likewise continue as deputy chairs.
The Centre wrapped up in its conference in Lappeenranta, eastern Finland, with more than 2,500 registered attendees. On Saturday they re-elected Finance Minister Annika Saarikko as chair by a wide margin over challenger Paavo Väyrynen. All three parties sought to clarify their policy programmes in the run-up to next spring's parliamentary elections.