# Sunset clauses and ex-post evaluation: Popper's piecemeal reform applied to Spain's laws

> Karl Popper's piecemeal social engineering treats each reform as a limited experiment to be watched and corrected. Spain already has the pieces to do this with its laws: Law 50/1997 and Royal Decree 286/2017 select rules for ex post evaluation, and Law 27/2022 created an evaluation system with an independent agency. The radical-centre proposal joins them to a sunset clause: every major law states in advance what success looks like, the agency evaluates it, and its new powers and burdens lapse on a known date unless parliament renews them on the evidence.

- URL: https://www.radicalcentre.eu/en/articles/sunset-clauses-evaluation-popper-piecemeal-reform
- Language: en
- Publisher: radical centre / centro radical
- Published: 2026-10-26
- Topic: Democracy & institutions
- Author: radical centre
- Licence: CC BY 4.0

## Key points

- Popper's piecemeal social engineering pursues one goal at a time so side effects can be spotted and corrected; the Stanford Encyclopedia of Philosophy says it parallels the critical testing of scientific theories.
- Spanish law already requires ex post evaluation of selected rules for effectiveness, efficiency and sustainability (Law 50/1997, art. 28; Royal Decree 286/2017, art. 3).
- The 2024 Annual Regulatory Evaluation Report tracks how much of the plan was approved (44.95% of 198 initiatives) and has no chapter on what the evaluated laws achieved.
- Germany let its post-9/11 security powers expire unless renewed, evaluated them, and in 2011 proposed dropping powers that had gone unused.
- Our proposal: major laws carry a stated test, an independent evaluation by the state evaluation agency and a sunset date for new powers and burdens, with renewal by a simple majority vote in parliament.

Karl Popper wanted politics to learn the way science learns. In *The Open Society and Its Enemies* (1945) and *The Poverty of Historicism*, he defended what he called piecemeal social engineering: pick one concrete evil, design a limited reform against it, watch what happens and correct it. The Stanford Encyclopedia of Philosophy puts it neatly: the method "parallels precisely the critical testing of theories in scientific investigation." Each action pursues one goal at a time, so its side effects can be spotted and fixed.

We set out the book itself in our [explainer on Popper](/en/articles/karl-popper-the-open-society-explained). This piece takes the method and turns it into a rule for how Spain makes laws. A law is a conjecture about the world: if we do this, that will happen. A law can be tested, and the sunset clause is the date of the test.

## What Spain already has

Spain wrote evaluation into its law-making years ago, and the framework is better than its reputation. Article 25 of Law 50/1997 on the Government requires an annual regulatory plan, and that plan must flag the rules that will be reviewed for their results once in force. Article 28 then requires the Council of Ministers to approve, before 30 April each year, a report that includes those reviews. They must examine whether the rule achieved what it was passed for, whether it imposes unnecessary burdens and whether it is sustainable, and the report can recommend amending or repealing it. The ministry of the presidency also checks that each draft's impact assessment includes a system for evaluating the rule afterwards where one is required.

Royal Decree 286/2017 fills in the detail. It lists eight criteria for picking the rules to evaluate, among them a significant budgetary cost or saving, a significant change in administrative burdens, a relevant impact on constitutional rights, effects on competition and SMEs, and relevant impacts by gender and on children and families. It creates an inter-ministerial board to draft the plan and the report.

Then Law 27/2022 built a wider system for evaluating public policies. Ministries must evaluate, before and after, the policies with notable budgetary impact or major social or economic effects; those lasting four years or more also need a mid-term evaluation. Final evaluation reports must be published within a month, and the responsible body has two months to answer the recommendations, explaining any it rejects. The law authorised a state evaluation agency, whose statute Royal Decree 65/2026 approved in February, attached to the Ministry of Economy; it must report to the Cortes every year.

The weak point shows in the annual report itself. The 2024 edition, published on the Transparency Portal, is proud that this is the fifth consecutive year the government has approved and published it. Its chapters count initiatives: 44.95% of the 198 in the 2024 plan had been approved, and another 15.66% were in progress. They follow plan execution ministry by ministry and list the EU directives transposed. We found no chapter on what the laws selected for evaluation actually achieved. Spain measures how fast it legislates and says little in public about whether its laws work.

## What a deadline does

Other countries add the missing piece with a date. After the 2001 attacks, Germany gave its security services wider powers and made them temporary. The 2007 follow-up law required an evaluation, and the powers ran until 10 January 2012. In 2011, as the Bundestag's own report explains, the government proposed keeping for four more years only the powers the evaluation had found indispensable. It dropped the power to request information on postal traffic and the power to use technical means inside homes for officers' protection, both unused during the evaluation period. That is Popper in a committee room: the evidence came in, and the parts of the law that had failed to earn their place lapsed.

The UK wrote the same logic into the Coronavirus Act 2020. Section 89 makes the Act expire two years after it was passed, and section 98 required a Commons vote every six months on whether its temporary provisions should continue, with a duty on ministers to end them within 21 days if the vote failed. The European Commission works with a cousin of the idea, its "evaluate first" principle, under which evaluation of an existing law comes before any work on revising it.

## The proposal

Join the Spanish pieces to a German-style clock.

Every law that meets the Law 27/2022 threshold, or the criteria of Royal Decree 286/2017, states its test when it is drafted. The impact assessment says what the law is for, which indicator will show it, what result would count as failure and when the evaluation will happen. The [comparison of real alternatives](/en/articles/compare-real-alternatives-impact-assessment-proposal) we proposed for that same document gives the evaluator a baseline to measure against.

The new powers, obligations, subsidies and administrative burdens such a law creates carry a sunset date, typically between five and eight years out, set in the text. Rights already acquired and contracts already signed are protected through the transition.

A year before the date, the state evaluation agency publishes its evaluation, including who has gained and who has lost. The government then proposes to renew, amend or let the provisions lapse, and parliament votes. Renewal needs a simple majority. Parliament can renew in part, as Germany did.

The annual evaluation report gains a real chapter: the results of every law that reached its evaluation date, and what was decided.

For the existing stock, the annual plan schedules a tranche of older laws each year to be reviewed the same way. At Democracia 21's launch on 10 October, Miriam González called for removing the obstacles facing people who start a business ([our overview of her speech](/en/articles/democracia-21-miriam-gonzalez-proposals-radical-centre) maps the rest). A scheduled review of the stock lets any government do that with the evidence in hand, one tranche at a time.

The left gets a guarantee that laws are judged by what they do for the people they were written for, with a public account of winners and losers. The market-liberal tradition gets a smaller stock of rules, laws that must prove their worth to survive and expiry dates known from day one, which is a form of legal certainty. The piece that belongs to neither camp is Popper's falsifiability made into procedure: each major law names in advance the evidence that would show it wrong, and its renewal depends on that evidence.

Two design choices keep this from feeding the [vetocracy](/en/articles/what-is-vetocracy-fukuyama-dunkelman) we wrote about earlier this fortnight. Renewal by simple majority stops a blocking minority from using the deadline as a hostage. And the vote comes on a fixed date with the evaluation already published, so the debate happens over evidence. [Policy pilots](/en/articles/policy-pilots-spain-experiment-first) test an idea before it becomes law; the sunset clause keeps testing it afterwards, for as long as it stays on the books.

## FAQ

### What is a sunset clause?

A provision that makes a law, or part of it, expire automatically on a set date unless the legislature renews it. The UK's Coronavirus Act 2020, for example, was written to expire two years after it was passed.

### Does Spain evaluate its laws after they are passed?

On paper, yes. The annual regulatory plan picks rules for ex post evaluation using criteria in Royal Decree 286/2017, and the annual evaluation report can recommend amending or repealing them. In practice the published report concentrates on how much of the plan was approved.

### What did Karl Popper mean by piecemeal social engineering?

Reform by limited, specific steps, each aimed at one concrete problem, watched closely and corrected when it goes wrong. Popper set it against utopian engineering, which remakes society to a single blueprint that cannot be tested.

### Wouldn't sunset clauses create legal uncertainty?

The expiry date is written into the law from the start, so everyone knows it. Rights and contracts already acquired stay protected, and renewal needs only a simple majority, so a minority cannot use the deadline to block a law that works.

## Sources

- [Ley 50/1997, de 27 de noviembre, del Gobierno](https://www.boe.es/buscar/act.php?id=BOE-A-1997-25336), BOE (1997)
- [Real Decreto 286/2017, por el que se regulan el Plan Anual Normativo y el Informe Anual de Evaluación Normativa](https://www.boe.es/eli/es/rd/2017/03/24/286/con), BOE (2017)
- [Ley 27/2022, de institucionalización de la evaluación de políticas públicas en la Administración General del Estado](https://www.boe.es/eli/es/l/2022/12/20/27/con), BOE (2022)
- [Informe Anual de Evaluación Normativa 2024](https://transparencia.gob.es/content/dam/transparencia_home/publicidadactiva/normativa/pan2024/IAEN2024PT.pdf), Gobierno de España, Portal de la Transparencia (2025)
- [Antiterrorregelungen sollen verlängert werden](https://www.bundestag.de/webarchiv/textarchiv/2011/35685287_kw38_sp_antiterror-206224), Deutscher Bundestag (2011)
- [Coronavirus Act 2020, section 89: Expiry](https://www.legislation.gov.uk/ukpga/2020/7/section/89), legislation.gov.uk (2020)