The news comes as the nationalistic politics of both countries has prompted increased tensions between Brussels.
One EU source told Reuters: “We are confident that the ECJ will confirm validation, then they [Poland and Hungary] must abide by the decision.
“If they don’t, then they will face consequences, both financial and political.
“No more opt-outs, there is no more ‘one foot in and one foot out.’ We are going to be very tough on this.”
Both Hungary and Poland refused to support a quota system of refugee resettlement in 2015.
The EU has frequently criticised both countries for what it views as weak responses to the ongoing refugee crisis.
The EU Commission has also before accused nationalist Hungarian Prime Minister Viktor Orban of conducting an “assault on political freedoms” before the ECJ.
News of fresh tensions between the EU and the two member states comes after Hungary last week vowed to defend Poland against an “unjust” clampdown by Brussels chiefs.
The Czechs also sided with their eastern European ally after the EU Commission threatened to strip Warsaw of voting rights after a series of judicial reforms.
Brussels claims the reforms, which see the Polish government gain more control over the courts, are a threat to democracy.
But Hungary’s Deputy Prime Minister, Zsolt Semjen, hit out at the decision.
He said: “We shall defend Poland in the face of an unjust, fabricated political procedure.”
The EU Commission has given Warsaw’s Law and Justice (Pis) party three months to change reverse its reforms.
But Poland has remained steadfast and claimed like-minded allies such as Hungary would veto the ultimate sanction of suspending Poland’s voting rights in the bloc.