Ley 30230 was introduced in 2014 and has been a source of controversy ever since. Designed to facilitate the inflow of foreign investment, its most worrying and contested aspect has been its weakening of the ability of communities to control the territory which they regard as theirs by ancestral right.

But the aspect that has caused most aggro to the companies has been the decision that requires them to pay the costs of their supervision by the state, in particular by OEFA, the supervisory agency within the Environment Ministry.

The tax, known as the Aporte por Regulación (or APR), requires companies to hand over a percentage of profits (not more than 1 per cent) into the OEFA budget. Were this tax to be repealed, OEFA, already desperate for funding, would, it claims, lose 70 per cent of its budget.

Ojo Público, the NGO which has led the battle throughout, reports claims by OEFA lawyer Aníbal Quiroga León that the real motive behind the opposition is to weaken regulation of the sector.

Numerous efforts by companies to secure repeal have failed over the past five years. But now two companies, Cerro Verde and Perubar, have taken the matter to the Constitutional Tribunal declaring the tax unconstitutional and illegal. No date has been set for its ruling on this matter.