Carbon markets and Article 6 counsel.

The old shape of this decision was simple enough that it never reached a legal department twice. A sustainability team modeled residual emissions, procurement ran a tender, a broker delivered a retirement certificate, and counsel saw a purchase agreement once, if at all. That shape survived because nothing downstream ever tested it. Between the Article 6.4 standards entering force on 9 October 2024 and the first issuance under the mechanism on 26 February 2026, three things happened at once that test it: the credit acquired a government authorization, the authorization acquired a defined scope, and the scope acquired a date.

What the buyer now holds is a document class without a settled form. Norton Rose Fulbright's February 2025 guide sets out what a host-country letter of authorization has to record: the authorization date, the designated national authority, the crediting program, the project identification and location, whether the mitigation outcome is authorized toward a nationally determined contribution or toward other international mitigation purposes, and the host state's commitment to apply a corresponding adjustment. The UNFCCC secretariat is still developing a standardized template, and in the meantime interim templates circulate from the World Bank Group and from Verra. A document class with no settled form is a document class somebody has to read line by line.

The compliance universe underneath it is not small and it is not new. IETA's Greenhouse Gas Market Report 2025 counts 38 emissions trading systems in force worldwide, covering more than 12 billion tonnes of carbon dioxide equivalent — roughly 23 percent of global greenhouse gas emissions — with about USD 70 billion of auction revenue in 2024 and roughly USD 373 billion raised since 2008. None of that is a reason to hire a lawyer. It is the reason the question stopped being optional: a company inside any of those systems already carries a carbon liability that its finance function books, and a liability that finance books is a liability legal will eventually be asked to defend.

Sartori's London interview cohort is 750 structured interviews with legal buyers in the city. Within it, 118 were general counsel and heads of legal at companies carrying a public net-zero commitment, interviewed across a 24-month window. Sixty-one percent of that segment said carbon-credit purchasing sat with procurement or sustainability at the point of signature and reached the legal department only at retirement or surrender. Forty-seven of the 118 had a written credit-title diligence protocol at all; 19 of those 47 required a host-country letter of authorization to be on file before payment. The gap between 118 and 19 is where the exposure sits unowned.

The default is to rent it, and the default is rational. The Association of Corporate Counsel's 2025 Chief Legal Officers Survey, published on 28 January 2025 and built on 772 chief legal officers across 20 industries and 48 countries, found 43 percent expecting to increase their use of outside counsel, with global regulatory change named as a primary driver. A panel is cheaper than a payroll line for as long as the work is episodic. The narrower question is not whether the work matters but whether it has become recurring and dated, because those two words, not importance, are what move a seat inside a company.

A head of legal at a European airline group put it plainly to us: the cancellation instruction is the one line in the book where legal signs and finance pays, and nobody in the group had written down who checks that the corresponding adjustment was applied before the surrender goes in. That is not a compliance failure. It is an ownership vacancy, and it is the most common finding in this segment of the cohort.

A corresponding adjustment is the accounting act that stops one tonne being counted twice. When a host country authorizes the international transfer of a mitigation outcome, it undertakes to add that quantity back to its own emissions balance so that a buyer's country, or a buyer's compliance scheme, can subtract it. That undertaking is what a buyer is really purchasing; the credit is the receipt for it. CORSIA requires the adjustment expressly for the units it accepts, and buyers outside aviation have begun demanding correspondingly adjusted credits as a quality signal rather than a compliance necessity, on ceezer's November 2024 market reading.

Timing is the part that is easy to get wrong and expensive to fix. Legal certainty on an Article 6 unit attaches at the earlier of the first international transfer or of authorization, issuance, use or cancellation, which is why counsel close purchase contracts before first transfer rather than after it (Clyde & Co, December 2024). After that point the negotiation is about remedies, not terms. A legal department brought in at surrender is, definitionally, on the wrong side of that line.

Each bilateral agreement then writes its own arithmetic. Singapore's first Article 6 implementation agreement, signed with Papua New Guinea on 7 December 2023, requires developers to cancel 2 percent of authorized credits at issuance for overall mitigation, directs 5 percent of credits to the host country's adaptation needs, and permits Singapore-based firms to use eligible credits against up to 5 percent of their taxable carbon-tax emissions. The Ghana agreement of 27 May 2024 carries materially the same shares. By mid-2026 the Singapore book had reached 11 implementation agreements; Switzerland's, the longest-running, ran to 16 signed between October 2020 and November 2025. None of them is a template. Each is a set of percentages a buyer's counsel has to reconcile against the surrender the company actually intends to make.

Sartori's quarterly survey of London legal departments has run since 2019. Across the four most recent waves, 96 London respondents named a carbon-market or emissions-trading obligation somewhere in the business. Twenty-nine of those 96 could name the individual internally responsible for verifying that a credit's corresponding adjustment had been applied. The other 67 named an external firm, a broker, or nobody — and the third answer was more common than the first.

Coverage cuts against us here, and it is worth saying so. Sartori maps about 30,000 lawyers in London, and the honest limit of that map is visible in this practice: in three of the six carbon-adjacent London mandates, the person already doing the work held a sustainability or commercial title rather than a legal one. A lawyer map does not see somebody who is not filed as a lawyer, which means the candidate population for this seat is systematically larger than our own instrument can read.