In 1834 Dechamps was elected to the Belgian Chamber of Representatives, where his talent as an orator soon secured him a prominent position.

The great powers had imposed that treaty on Belgium and the Netherlands in 1834, but the latter had delayed accepting it in the hope that she might eventually obtain better conditions.

Deschamps, with many others, held that by this delay the Netherlands had forfeited her right to the advantages granted her by the Powers and they urged the Government to appeal to arms rather than to surrender any part of Belgian territory.

One of the provisions of the new bill enacted that religious instruction was to form an essential part of public education and to be under the control of the clergy.

After the defeat of his party in 1848 he became the leader of the Catholic minority in the Chamber of Representatives and retained that position for several years.