What legal grounds have UK courts accepted for Julian Assange's appeals against extradition to the U.S.?

1. The accepted free‑speech/First Amendment equivalence ground

High Court judges have recognised that a central legal question for appeal is whether, as a foreign national tried in the US, Assange could meaningfully invoke a First Amendment defence and therefore whether his removal would be compatible with the European Convention on Human Rights right to freedom of expression; the court said deprivation of that defence could make extradition incompatible with the ECHR (The Guardian; AP; BBC) ^{[1] [3] [2]}.

2. Prejudice at trial and nationality‑based disadvantages

UK judges have accepted that there are arguable prospects that Assange could be prejudiced at trial or punished because he is not a US citizen — a point the court flagged as a legitimate ground for appeal absent “satisfactory” assurances from the US about how proceedings would treat him (The Guardian; CPS) ^{[1] [4]}.

3. Death‑penalty and specialty protections: assurances narrowed the issues

Courts have repeatedly demanded and then evaluated US assurances on the death penalty and related protections; at different stages judges accepted some assurances as “satisfactory” (thus refusing leave to appeal on death‑penalty grounds) while keeping other human‑rights and procedural questions open — the High Court in March and May 2024 gave the US time to provide or clarify assurances before allowing certain appeals to proceed (RSF; The Guardian; BBC) ^{[5] [6] [2]}.

4. What has been refused or already dismissed

Other legal grounds raised by Assange — including broader claims that the extradition is an abuse of process, that the prosecution is essentially political and therefore barred under extradition law, or earlier mental‑health arguments that previously led to a refusal to extradite in 2021 but were overturned after US assurances — have been rejected at various points by UK judges, leaving the present appeals focused on the narrower speech, prejudice and assurances issues (The Guardian; The Guardian 2023; SMH; JURIST) ^{[6] [7] [8] [9]}.

5. How the courts have handled the procedural path: leave to appeal, adjournments and conditional permissions

The pattern in the UK courts has been procedural caution: judges often grant “leave” to appeal only on specific grounds they consider to have a “real prospect of success” and will adjourn or limit leave if the US can provide satisfactory assurances on discrete issues — a process that keeps some constitutional questions alive while enabling extradition to proceed if courts accept the US guarantees (The Guardian; RSF; AP) ^{[1] [5] [3]}.

6. Competing narratives, agendas and legal strategy

Supporters frame the accepted grounds as vindication of press‑freedom concerns, while US prosecutors and some UK authorities emphasise that ordinary criminal law — not a political prosecution of journalism — is at issue; human‑rights NGOs such as RSF welcome the High Court’s narrow openings but also press for the wider political‑speech arguments to be recognised, exposing an implicit agenda by each side to shift the case from technical treaty or procedure disputes to a broader debate about investigative journalism and national security (RSF; The Guardian; JURIST) ^{[5] [1] [9]}.

Conclusion — where the law stands now

UK courts have accepted only a small set of high‑stakes legal questions for further appeal: whether extradition would violate ECHR free‑speech protections because Assange might be stripped of a meaningful First Amendment defence, whether his nationality could prejudice his trial or sentence, and whether US assurances (on death penalty and specialty protections) are adequate; other grounds have been dismissed or awaiting resolution contingent on those assurances, leaving the legal fight concentrated on narrow but potentially decisive constitutional and human‑rights issues (AP; BBC; CPS) ^{[3] [2] [4]}.