As discussed here a few weeks ago when the long parliamentary discussions began, the code sets down national standards aimed at ensuring the really important bits of the nation's forests are protected from development.
The main force pushing the reforms is Aldo Rebelo, head of the Communist Party of Brazil (PCDoB).
His rationale is that the current code works against small-scale farmers. Regional rivals that compete with Brazil as food exporters are not expected to labour under such a handicap, supporters say.
There will also be an amnesty for small-scale landowners who illegally chopped down trees prior to July 2008.
There's a dichotomy over development here that reflects a wider global dilemma.
Sure, farmers can exploit more of their land if they clear hilltops and riverbanks.
But what happens if strong rains come? How are the chances increased that water will pour down the newly naked slopes and wash soil away?
If drought comes to the Amazon again, as some climate forecasts suggest it will in ever stronger form, how will the removal of riverbank protection exacerbate water shortages that will affect everyone - farmers included?
Yet Mr Rebelo and agricultural leaders argue that Brazil needs the extra farmland in order to feed its own growing population and preserve an export capability.
The reforms have to pass the Senate before they can come into force, and President Dilma Rousseff has vowed to veto anything with an amnesty in it - so the issue isn't completely resolved.
And the country's environmental leaders are in no doubt which way the decision should go.
A group of 10 former environment ministers has sent a letter to President Dilma and to members of congress urging them to reject the reforms, describing them as a "retrograde step".
(You can find the letter in Portuguese on former minister Marina Silva's website - if anyone's seen an English version, please post a link - I haven't.)
"Long before the world fully awoke to the importance of its forests, Brazil had taken the pioneering step of formally establishing the need for their conservation in its legislation," they write.
As the Forest Code dates back to 1965, it was something of a pioneering step, certainly for a developing country.
They say the code "has been the single most relevant institutional basis for the protection afforded to forests and all the other forms natural vegetation in Brazil, as well as protecting the biodiversity associated to them, the water resources they protect and the ecological services that they provide.
"Agricultural policy can benefit from the services that the standing forests offer and achieve new and more advanced levels of competitiveness and productivity."
They also point to a conflict between what Brazil says it wants to achieve in the climate change arena - a cut in emissions of more than one-third by 2020 - and reducing protection for forests.
With deforestation being the country's largest source of emissions, reversing deforestation is also the only feasible way for it to meet that target.
Yet just last week came news that Amazon deforestation had increased almost six-fold in just a year - an astonishing rise, and a trend large enough, if it continues, to guarantee the emissions target won't be met.
And the ministers link this to the Forest Code issue.
"The mere expectation that the amendment to the Forest Law and its consequent weakening would be approved set off a disturbing wave of renewed deforestation in the Amazon region, as has been unequivocally demonstrated by data recently released by the Brazilian Space Research Institute (INPE)," they write.
There is an international dimension to this.
In the run-ups to three successive UN climate conferences now, I've been told: "We won't finalise a comprehensive deal this time, but we might get something on REDD".
REDD - Reducing Emissions from Deforestation and forest Degradation - is envisaged as a scheme that would see rich countries funding poorer ones with significant forest resources, like Brazil, to preserve and enhance them, in the global interest of curbing climate change.
Well, REDD hasn't arrived... and probably can't, realistically, because a number of developing countries have said they won't agree measures unless they form part of a comprehensive global climate treaty - which remains as elusive as ever.
Brazil, like Indonesia, has said it would go further on reducing emissions and deforestation with Western support... which isn't forthcoming, because there's no global deal.
Those are the international politics in brief.
But there are also implications for Brazil itself.
Not only a regional leader now, it's also emerged as a global leader, certainly on the stage of nature protection.
At last year's UN biodiversity summit, no country was more visible, more vocal, more engaged in all the issues under discussion than Brazil.
Criticisms of Western nations coalesce around the notion that if you want to claim environmental leadership, do it with actions rather than words.
The same criticisms will, eventually, be levelled at developing countries that do not protect what they have - especially in the face of advice that protection is in their long-term economic interest.