Unless you do something so horrible that it is talked in the news/wide industry, rarely any company will contact your previous employers. They may ask 'so, why did you leave company X?' but in 20 or so years, I never had a company in Portugal ask for an actual reference. (I had in the UK, US and Switzerland though)

While I am not sure, I think legally here is a very grey area as employment information is protected, but I'm not 100% sure.