Ian Traynor (Report, 9 December) makes some powerful points for and against the Transatlantic Trade and Investment Partnership being negotiated between Washington and Brussels. There is some difficult negotiating ahead and ultimately a rough ride during the ratification process in the European parliament, since the Lisbon treaty gave the parliament the final say over all trade agreements. The Europeans surely will want some say over the limits of US companies tax avoidance manoeuvres in Europe. Equally, there will be a major stand-off between US and European-style regulation. They will need to be harmonised to bring the full benefits to both sides, but at the moment they are poles apart. Exactly where the compromise ends up matters.

Globally TTIP is one leg of a triangle of deals. There are the Trans-Pacific Partnership negotiations between the US and 11 Asian Pacific countries, but dominated by Japan-US bilateral trade, and the EU-Japan Free Trade Agreement now in the final phase of negotiations. But if we want to negotiate from a position of strength, we should seal the deal with Japan first, getting Tokyo on board with our high standards of consumer, environmental and safety regulations. The EU-Japan deal would be the world’s biggest trade agreement, with only the TTIP as a potentially bigger deal. With that in the bag, Brussels – and Tokyo – would have powerful leverage over Washington to ensure a TTIP agreement shaped in our interests and reflecting our concerns.

Glyn Ford

Former MEP and member of the international trade committee

• Some 340 cases are known to have gone to arbitration under existing trade and investment agreements with ISDS, a model in which decisions are made by arbitrators who are not accountable to anyone, under a process in which civil society has no right to know who has given evidence, what that evidence was, or what arguments were made, and has no right of appeal. Hence in a dispute between a company and a government, the decision may negate democratic government policy.

Jenny Parsons

Cottingham, East Yorkshire

• Contrary to your report, the investor-state dispute settlement provisions in the proposed TTIP could well give corporations more powers over national sovereignty. The government’s own report on ISDS, by LSE Enterprise, found that the analogous Nafta pact permitted US corporations to mount 34 compensation claims in 15 years against Canada over corporate business exclusion because of state restrictions, such as health and environmental regulations. These claims amounted to $5bn at an average cost and even when unsuccessful, cost $4m to the defending party. Under TTIP the amount of cases and costs would probably be higher because of the greater volume of business between the US and UK. So it is incorrect to dub European fears “not necessarily rational”. They could be, for example, a significant financial deterrent to any “de-privatisation” of the NHS.

Bryn Jones

Bath

• You say governments could “force firms vying for public contracts to pay a living wage”. But already, under a treaty between France and Egypt including ISDS, French multinational Veolia is suing the Egyptian government for compensation after it dared to raise the minimum wage. The Guardian has an immense power for good when you throw its full weight into a campaign, as you have done admirably over NSA and GCHQ. But you’ve done little to publicise the TTIP, which is a far greater long-term threat to democracy. Please join the fight against TTIP and ISDS before it’s too late.

John Heawood

York