The Mutual Assistance Act and its treaty framework

The statute of 1981 and its place in the system

The Federal Act of 20 March 1981 on International Mutual Assistance in Criminal Matters, cited in German as IRSG, in French as EIMP and in English as IMAC, is the general statute for every form of cooperation in criminal matters between Switzerland and foreign states.¹ It covers four forms of cooperation, which the Act calls its parts: extradition, what it terms “other mutual assistance” (the gathering and transmission of evidence and the seizure and handing over of assets), the transfer of criminal proceedings and the enforcement of foreign criminal judgments. The third part is by far the most important for a financial centre, because it is the route through which foreign prosecutors obtain bank documents, witness statements and the freezing of accounts. Where Switzerland has concluded a treaty with the requesting state, the treaty takes precedence and the Act fills its gaps. The Federal Supreme Court applies the principle that the more favourable rule for cooperation prevails, so that the domestic statute may be used to grant assistance where a treaty would permit a refusal.²

The most important multilateral instrument is the European Convention on Mutual Assistance in Criminal Matters of 20 April 1959, together with its two additional protocols. Relations with the member states of the European Union are further shaped by the Convention implementing the Schengen Agreement, to which Switzerland became a party through its association with Schengen. A document prepared for European prosecutors under the SIRIUS project summarises the resulting position: requests from Switzerland’s European partners rest on the Mutual Assistance Act and on the 1959 Convention and its Second Additional Protocol, the Schengen Implementing Convention and the Budapest Convention on Cybercrime, while bilateral treaties and reciprocity complete the picture.³ The Second Additional Protocol and the Schengen rules have one consequence of great practical weight. Prosecutors in Germany, France, Italy or Austria may send their requests directly to the competent Swiss prosecution authority, without passing through the Federal Office of Justice in Bern. Much of the daily traffic between Zurich and its neighbours therefore never appears in the central statistics.

Among bilateral treaties the one with the United States has a special place in the history of the financial centre. Signed in Bern on 25 May 1973, it was the first comprehensive mutual assistance treaty of the United States. President Ford, transmitting it to the Senate in February 1976, described it as “the first major international agreement by the United States aimed at obtaining information and guidance needed for criminal investigations” and observed that American agencies had “frequently encountered severe difficulties in obtaining needed information from Swiss banks because of banking secrecy laws”.⁴ The treaty, which entered into force in 1977, contains special rules on organised crime that allowed assistance in tax matters where the tax offence was linked to an organised criminal group.⁵ It was the model on which Switzerland later negotiated treaties with other common law states. The Act of 1981 itself was drafted partly in the light of the experience with the American treaty, which had shown that banking secrecy could be reconciled with cooperation as long as a judicial procedure protected the customer.

Dual criminality and reciprocity

The first of the classical principles is dual criminality. Swiss authorities may apply coercive measures on behalf of a foreign state only if the facts described in the request would also be punishable under Swiss law. Coercive measures include the search of premises, the seizure of documents, the production order addressed to a bank and the freezing of an account. Pascal Gossin, writing as head of the international mutual assistance section of the Federal Office of Justice, summarised the rule by saying that coercive measures may be ordered if the offence described in the request is also punishable in Switzerland.⁶ The test is applied abstractly. The Swiss authority asks whether the conduct described, transposed to Switzerland, would fall under a Swiss criminal provision, without examining the elements of the foreign offence or the guilt of the accused. In economic cases the relevant Swiss provisions are usually fraud, criminal mismanagement, forgery of documents, bribery of foreign public officials and money laundering. Because the Swiss money laundering offence covers the laundering of proceeds of any felony and, since 2016, of proceeds of a qualified tax offence, a foreign request framed as a money laundering investigation can reach assets whose origin lies in conduct that Swiss law would not otherwise treat as a predicate offence.

Where no coercive measure is needed, dual criminality is not required. The service of documents, the transmission of information already publicly available or the questioning of a willing witness may be granted even if the foreign offence has no Swiss equivalent. The SIRIUS guidance mentions one statutory exception to the requirement of dual criminality, which allows coercive measures where they serve to exonerate a defendant or concern sexual acts with minors.⁷

The principle of reciprocity is less visible in practice. Where there is no treaty, Switzerland may make assistance dependent on an assurance that the requesting state would grant assistance in a comparable case.⁸ The Federal Office of Justice obtains such assurances in cases involving states with which no treaty exists, for example in parts of the Gulf region, Asia and Latin America. For a financial centre whose clients come from every continent, the possibility of cooperating without a treaty is significant, since many of the states from which illicit assets originate have never concluded a mutual assistance treaty with Switzerland.

Speciality

The principle of speciality limits the use that the requesting state may make of the evidence it receives. Under Article 67 of the Act, information and documents obtained through mutual assistance may not be used, directly or indirectly, in proceedings concerning offences for which assistance would be inadmissible. The SIRIUS guidance puts the rule in the form in which Swiss authorities communicate it to their foreign counterparts: the evidence “may not be used, neither directly or indirectly, in a criminal procedure concerning an offence for which assistance is not admissible”.⁹ Any other use requires the consent of the Federal Office of Justice. Every transmission of bank documents is therefore accompanied by a standard reservation, which reminds the foreign authority that the material may not be used to prosecute political offences, military offences or pure tax evasion.

Speciality is the principle that clients of Zurich banks understand least and practitioners in other countries tend to underestimate. A German public prosecutor who receives Swiss bank statements in a bribery investigation may use them to prove the bribe and the laundering of its proceeds. The German tax authority may not use the same documents to assess income tax on undeclared interest unless the conduct amounts to tax fraud in the Swiss sense or unless the information has been obtained through the separate channel of tax administrative assistance. German courts have in recent years examined the related speciality rule that attaches to extraditions from Switzerland in the cum-ex proceedings, which shows that Swiss speciality limits still have practical bite abroad.¹⁰

The fiscal exception and Article 3 paragraph 3

The fiscal exception was for decades the central pillar of the Swiss position. Article 3 paragraph 3 of the Act lays down the rule that a request “shall not be granted if the subject of the proceedings is an offence which appears to be aimed at reducing fiscal duties or taxes or which violates regulations on currency, trade or economic measures”. The same paragraph then admits two exceptions. A request may be granted under the third part of the Act, that is for the gathering of evidence and related measures, “if duty or tax fraud is the subject of the proceedings”. Under all parts of the Act, including extradition, a request may be granted if aggravated duty or tax fraud within the meaning of Article 14 paragraph 4 of the Federal Act on Administrative Criminal Law is the subject of the proceedings.¹¹

The distinction between tax fraud and tax evasion, which Part F places in its historical context, is therefore still the pivot of criminal assistance in tax cases. Tax evasion, the mere failure to declare income or assets, remains outside the scope of criminal mutual assistance. Tax fraud requires the use of forged, falsified or untrue documents such as accounts, salary statements or other certificates issued by third parties, or, under the case law, a deceitful edifice of lies. A foreign prosecutor who wishes to obtain Swiss bank documents in a tax case must therefore describe facts that fall within this narrower Swiss concept. The requirement is easier to meet than it appears, because false invoices, sham contracts and back-to-back loans are the usual instruments of large-scale tax evasion. The qualified form under Article 14 paragraph 4 of the Administrative Criminal Law Act, which concerns professional smuggling and serious fraud in the field of indirect taxes, was added in the course of the implementation of the FATF standards of 2008.

For indirect taxes the treaty framework goes further. The Schengen Implementing Convention and the agreement between Switzerland and the European Union on the fight against fraud oblige Switzerland to grant assistance in matters of excise duties, value added tax and customs, even for offences that do not amount to fraud in the Swiss sense.¹² A comprehensive analysis by Andreas J. Keller in the Archiv für Schweizerisches Abgaberecht distinguishes accordingly between direct taxes, where the traditional limitation to tax fraud applies, and indirect taxes, where the Schengen rules and the qualified tax fraud extend cooperation, and examines the effect of the tax money laundering offence introduced by the GAFI legislation of 2016.¹³ That offence has blurred the boundary, because a foreign request for evidence relating to the laundering of the proceeds of a serious tax offence is a request concerning money laundering, for which the fiscal exception does not apply.

Political offences, human rights and proportionality

The political offence exception in Article 3 paragraph 1 of the Act and the human rights safeguards of Article 2 play a smaller role in financial cases than in extradition. They become relevant when a request comes from a state whose criminal justice system is suspected of pursuing opponents of the government or of expropriating businesses through criminal proceedings. The Act excludes the political character of an act from consideration in cases of genocide, crimes against humanity, war crimes and particularly reprehensible acts.¹⁴ In financial matters the more frequent question is whether a request concerning an alleged embezzlement in a state company is in reality part of a political struggle, for example after a change of government. The Swiss authorities then examine whether the foreign proceedings meet the minimum procedural guarantees of the European Convention on Human Rights and the International Covenant on Civil and Political Rights. Where doubts exist, assistance may be granted subject to guarantees under Article 80p of the Act. The Federal Office of Justice described in its annual report for 2023 a three-tier practice that sorts states according to their human rights record and attaches monitoring mechanisms to cooperation with the least reliable.¹⁵

Proportionality completes the list of principles. The Swiss executing authority may transmit only what is potentially relevant to the foreign investigation. Since the foreign authority cannot know in advance which documents will prove useful, the Swiss courts apply a generous standard of “potential usefulness”, which allows the transmission of the complete documentation of an account over the relevant period. The owner of the account may argue that particular documents have no connection with the facts described in the request. The argument succeeds only exceptionally, because the courts consider that the foreign authority is better placed to assess relevance. Practitioners who defend a client in Zurich must therefore concentrate their efforts on the few points where a precise objection can be made, such as accounts clearly unconnected to the facts or periods that lie long before the alleged offence.

Notes

1. Federal Act of 20 March 1981 on International Mutual Assistance in Criminal Matters (Mutual Assistance Act, IMAC), SR 351.1, bilingual German–English text at droit-bilingue.ch, https://www.droit-bilingue.ch/en-de/3/35/351.1-index.html. ↩
2. BGE 137 IV 33 of 9 November 2010, consid. 2.2.2, https://servat.unibe.ch/dfr/bge/c4137033.html: domestic law “reste toutefois applicable aux questions non réglées […] et lorsqu’il est plus favorable à l’entraide” (Günstigkeitsprinzip). ↩
3. Eurojust / SIRIUS project, “Requesting mutual legal assistance in criminal matters from Switzerland”, last update 21 December 2023, https://www.eurojust.europa.eu/sites/default/files/assets/requesting-mla-in-criminal-matters-from-switzerland.pdf. The document notes that direct contact between judicial authorities is permitted between states party to the Second Additional Protocol or to the Schengen Implementing Convention. ↩
4. Gerald R. Ford, “Message to the Senate Transmitting the United States-Switzerland Treaty on Mutual Assistance in Criminal Matters”, 18 February 1976, The American Presidency Project, https://www.presidency.ucsb.edu/documents/message-the-senate-transmitting-the-united-states-switzerland-treaty-mutual-assistance. Ford emphasised the treaty’s value for cases involving organised crime. ↩
5. Treaty between the Swiss Confederation and the United States of America on Mutual Assistance in Criminal Matters of 25 May 1973, SR 0.351.933.6, in force since 23 January 1977. The Federal Office of Justice publishes the English text at https://www.rhf.admin.ch/dam/rhf/en/data/strafrecht/rechtsgrundlagen/sr-0-351-933-6-e.pdf. ↩
6. Pascal Gossin (Federal Office of Justice), “International Mutual Legal Assistance in Switzerland”, UNAFEI Resource Material Series No. 77, https://www.unafei.or.jp/publications/pdf/RS_No77/No77_07VE_Gossin.pdf. The paper also notes that most requests are executed by the cantons. ↩
7. Eurojust / SIRIUS, “Requesting mutual legal assistance in criminal matters from Switzerland” (2023), https://www.eurojust.europa.eu/sites/default/files/assets/requesting-mla-in-criminal-matters-from-switzerland.pdf, section on grounds for refusal. ↩
8. Art. 8 IMAC: assistance is as a rule granted only if the requesting state grants reciprocity (para. 1). Reciprocity is not required for service of documents or where the execution of the request appears advisable because of the nature of the offence or the need to combat certain offences, among other cases (para. 2), https://www.droit-bilingue.ch/de-fr/3/35/351.1-8-12.html. ↩
9. Eurojust / SIRIUS, “Requesting mutual legal assistance in criminal matters from Switzerland” (2023), https://www.eurojust.europa.eu/sites/default/files/assets/requesting-mla-in-criminal-matters-from-switzerland.pdf, section on speciality. ↩
10. Mayeul Hièramente, “Der rechtshilferechtliche Spezialitätsgrundsatz im Steuerstrafrecht: eine kurze Einordnung der CumEx-Entscheidung des 1. Strafsenats, 1 StR 187/23 v. 20.9.2023”, WisteV, 28 December 2023, https://wistev.de/journal/2023/12/28/der_rechtshilferechtliche_spezialitaetsgrundsatz_im-steuerstrafrecht/. The decision concerns the speciality rule of Art. 14 of the European Convention on Extradition after an extradition from Switzerland, not the speciality reservation attached to other mutual assistance under Art. 67 IMAC. ↩
11. Art. 3 para. 3 IMAC, English text at droit-bilingue.ch, https://www.droit-bilingue.ch/de-en/3/35/351.1-3-7.html. The second sentence was amended by the Federal Act of 3 October 2008 implementing the revised FATF Recommendations, in force since 1 February 2009. ↩
12. Convention implementing the Schengen Agreement, Art. 50 para. 1, EUR-Lex, https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:42000A0922(02) (“mutual assistance as regards infringements of their laws and regulations on excise duties, value added tax and customs duties”); Federal Department of Foreign Affairs, Europe Division, “Betrugsbekämpfung”, https://www.europa.eda.admin.ch/de/betrugsbekaempfung, on the Cooperation Agreement with the EU to combat fraud of 26 October 2004 (SR 0.351.926.81), which covers smuggling and other offences concerning indirect taxes such as customs duties, VAT and excise duties and gives the parties the same instruments of administrative and mutual legal assistance as in their own proceedings. ↩
13. Andreas J. Keller, “Rechtshilfe und Auslieferung in Steuerstrafsachen, unter besonderer Berücksichtigung der Steuergeldwäscherei”, Archiv für Schweizerisches Abgaberecht (ASA) 89 (2020/21), No. 3, pp. 107–146, https://asa.weblaw.ch/asaissues/89/3/rechtshilfe-und-ausl_9e3c8bb86e.html. ↩
14. Art. 3 paras 1–2 IMAC, English text at droit-bilingue.ch, https://www.droit-bilingue.ch/de-en/3/35/351.1-3-7.html. ↩
15. Federal Office of Justice, International Legal Assistance Division, “Annual Activity Report 2023: Mutual Legal Assistance”, https://www.bj.admin.ch/dam/en/sd-web/MwzJIA6XWsan/jb-irh-2023.pdf, section on diplomatic guarantees and Art. 80p IMAC. ↩

For general information only. This article does not constitute legal or tax advice, does not replace advice on an individual case and creates no lawyer-client relationship. It reflects the legal position as of September 2025.