One of the most frequent mistakes in Swiss legal research is treating the question "which law applies here?" as a question about federal or cantonal competence, when the actual question is more precise: which specific provision within the applicable body of law controls this particular set of facts? Those are different questions, and conflating them sends research down the wrong path from the start.
This piece walks through the structure of the federal-cantonal relationship in Swiss law and explains how to identify the controlling norm for a given question. It is written for practitioners who work across cantonal jurisdictions and need to be confident that the norm they are citing is not superseded, preempted, or modified by a provision they have not found yet.
The Constitutional Basis: Kompetenzverteilung under the BV
The Swiss Federal Constitution (Bundesverfassung, BV, SR 101) allocates legislative competence between the Confederation and the cantons. The key provision is Art. 3 BV: cantons are sovereign to the extent that their sovereignty is not limited by the Federal Constitution. This creates a framework where federal competence is specific and enumerated, while residual legislative power remains with the cantons.
In practice, however, the major areas of private law, commercial law, and procedure are governed at the federal level. The Zivilgesetzbuch (ZGB, SR 210) and the Obligationenrecht (OR, SR 220) are federal statutes that apply uniformly throughout Switzerland. The Code of Civil Procedure (ZPO, SR 272), introduced in 2011, replaced 26 separate cantonal codes of civil procedure with a single federal instrument. These changes mean that for most private law questions, the controlling norm will be federal.
Where cantons retain significant legislative space is in areas such as public law, cantonal organization, certain taxation matters, and the implementation of federal mandates. Art. 46 BV requires cantons to implement federal law, but they have discretion in how they do so unless the federal statute specifies otherwise.
Where the Complexity Lives: Implementation Legislation
The real difficulty arises not at the level of basic allocation but at the level of implementation. A federal statute may set a rule and then delegate to cantons the authority to adjust certain parameters within defined limits. In these cases, the federal statute is the controlling norm in the sense that it defines the space, but the cantonal implementing ordinance (kantonale Ausführungsgesetzgebung) sets the operative provision that actually governs the fact pattern.
Consider a question about residential tenancy notice periods. The OR sets minimum standards for notice in Art. 266a ff. OR, but cantonal law may specify local notice requirements for apartments in designated areas. A practitioner advising a client in Canton Zurich needs both the federal floor (which cannot be contracted away under Art. 266o OR) and the cantonal position, because the controlling norm for a specific notice dispute may be the cantonal rule that is more protective, or the federal minimum that the cantonal rule must not fall below.
We are not saying that cantonal implementation law is always relevant. In many questions, the federal statute is complete and the cantons have not used their implementation space. The research task is to determine whether any such space has been used for your specific question in your specific canton.
The Hierarchy in Practice: How to Read Competing Provisions
Swiss federal law prevails over cantonal law by virtue of Art. 49 BV (Vorrang des Bundesrechts). This is not merely a priority rule: it means that cantonal legislation inconsistent with federal law is automatically invalid to the extent of the conflict. But note that Art. 49 BV applies to conflicts, not to gaps.
When federal law is silent on a question, cantonal law may fill the gap without conflict. When federal law regulates a field comprehensively, there is no room for cantonal variation even on matters the federal statute does not explicitly address. The Federal Tribunal has developed doctrine to distinguish between deliberate federal silence (where cantonal law may operate) and comprehensive federal regulation (where it may not). Key in this analysis is the concept of derogatorische Kraft des Bundesrechts: the preemptive effect of federal law.
A research step that is frequently skipped is checking whether the Federal Tribunal has characterized the federal statute in question as fully preemptive. A BGE decision that says the federal regulation in area X is abschliessend (exhaustive) settles the question of whether cantonal variation is permissible. The alternative BGE characterization, that the federal statute provides a Mindeststandard (minimum standard), means cantonal law may go further but not less far.
A Concrete Research Sequence
When a question lands on your desk that might involve both federal and cantonal elements, a productive sequence looks like this:
- Identify the federal statutory home: which article of the SR most directly addresses the question? The SR (
Systematische Rechtssammlung) at admin.ch is the authoritative text. - Read the relevant federal provision and its marginal notes (
Randtitel) for any explicit delegation to cantonal law. - Search BGE for Federal Tribunal decisions characterizing that federal provision as exhaustive or as a minimum standard. The characterization controls whether cantonal variation is possible at all.
- If cantonal variation is possible, locate the cantonal text. In German-speaking cantons, cantonal systematic law collections (
kantonale Gesetzessammlungen) are usually available online. The quality of these varies by canton. - Verify that the cantonal provision has not been amended since the BGE decisions you found. Federal Tribunal decisions may be interpreting a version of a statute that has since changed.
This sequence sounds straightforward, but step 3 is where practitioners frequently stop too early. A search that finds the federal provision and the general principle does not always surface the specific BGE decisions characterizing that provision's relationship to cantonal law.
What Changes When the Question Is Procedural
Since the entry into force of the ZPO on 1 January 2011, civil procedure is federalized for most matters. But the ZPO itself contains delegations to cantonal law in specific areas: conciliation authority organization (Art. 197 ff. ZPO), court organization, and some aspects of enforcement. A procedural question that seems straightforwardly federal may have a cantonal implementation layer that controls the operative answer.
The BGG (Bundesgerichtsgesetz, SR 173.110) governs the path from cantonal courts to the Federal Tribunal. It specifies which cantonal decisions are subject to appeal, what form the appeal must take, and what grounds are reviewable. Practitioners who advise clients on litigation strategy in Swiss proceedings need to understand both the substantive law hierarchy and the procedural hierarchy, because errors in one frequently appear in the other.
The Research Gap That Tools Often Miss
Most legal research tools present Swiss federal law clearly. The SR texts are well-indexed, and BGE decisions are searchable. The gap is at the cantonal level. There is no centralized index of cantonal implementation ordinances keyed to their federal parent statutes. Practitioners who need to know whether a given federal delegation has been exercised in a given canton are largely dependent on their own familiarity with that canton or their network of locally-based colleagues.
This is part of what we are building at Silex Legal: a traversal path that starts at the controlling federal norm and traces both the BGer interpretation of that norm and the cantonal application. The goal is not to replace the practitioner's judgment about whether cantonal variation is relevant to their question. It is to surface the fact that variation exists, and to provide the starting citation for investigating it, rather than leaving the practitioner to discover the gap through a missed argument in proceedings.
Identifying the controlling norm in Swiss law is a multi-step task that requires attention to the federal-cantonal relationship at every stage. The BV allocation, the preemption doctrine from Art. 49 BV, the specific characterization of each statute by the Federal Tribunal, and the cantonal implementation layer all interact. Treating any one of these as sufficient without checking the others is where research errors accumulate.
