The authority, exactly
An EU Blue Card issued by Finland gives the right to work only in Finland; holders of a Blue Card issued by another EU member state may still come to Finland for temporary business activity of up to 90 days without a separate Finnish permit. As with the specialist permit, a first Blue Card has to be applied for at a Finnish mission or an accredited application centre abroad, and the right to work begins once the permit itself is issued, not on the date of a D visa alone.