Rome I Regulation
The Rome I Regulation (Regulation (EC) No 593/2008 of the European Parliament and of the Council of 17 June 2008 on the law applicable to contractual obligations) is a regulation which governs the choice of law in the European Union. It is based upon and replaces the Convention on the Law Applicable to Contractual Obligations 1980. The Rome I Regulation can be distinguished from the Brussels Regime which determines which court can hear a given dispute, as opposed to which law it should apply. The regulation applies to all EU member states except Denmark. While the United Kingdom originally opted-out for the regulation they subsequently decided to opt-in.
The regulation sets out which law be used to interpret contracts with an international element (i.e. contracts agreed by parties in different countries). Pursuant to its Articles 28 and 29, the regulation came into force on 17 December 2009 and applies to contracts concluded after that date (beginning 18 December 2009).
Employment contracts 
Article 8(2), which supersedes article 6(1) of the 1980 Convention, says,
|“||To the extent that the law applicable to the individual employment contract has not been chosen by the parties, the contract shall be governed by the law of the country in which or, failing that, from which the employee habitually carries out his work in performance of the contract. The country where the work is habitually carried out shall not be deemed to have changed if he is temporarily employed in another country.||”|
The significant change is that the applicable law is that of the country "from which the employee habitually carries out" her work. It is intended to cover workers such as airline pilots who might not work "in" any particular country, but work "from" a country.
For a temporary worker posted in another country from her home country, article 8(2) makes the law of the home country apply. It would therefore appear that, for example, the employer of a Greek posted worker in Germany could rely on the lesser protections of Greek law. Article 7(2) of the 1980 Convention stated that 'Nothing in this Convention shall restrict the application of the rules of the law of the forum in a situation where they are mandatory irrespective of the law otherwise applicable to the contract'. Employment law is mandatory. However, article 7(2) was not retained in the Rome I Regulation. The replacement, article 9 defines mandatory provisions as,
|“||provisions the respect for which is regarded as crucial by a country for safeguarding its public interests, such as its political, social or economic organisation, to such an extent that they are applicable to any situation falling within their scope, irrespective of the law otherwise applicable to the contract under this Regulation.||”|
It is clear that employment law is applicable in any situation to a contract falling within its scope, though some have insisted, sceptically, that employment law may not be "crucial" in this sense, following older case law of the ECJ.
See also 
- Brussels Regime
- Rome II Regulation, relating to non-contractual obligations
- Posted Workers Directive
- Commission Decision of 22 December 2008 on the request from the United Kingdom to accept Regulation (EC) No 593/2008 of the European Parliament and the Council on the law applicable to contractual obligations (Rome I) (OJ L 10, 15.1.2009, p. 22)
- UK law had in fact already adopted such a position, Lawson v Serco Ltd  IRLR 289
- C Barnard, 'The UK and Posted Workers' (2009) 38 ILJ 122, and Arblade  ECR I-8453 (C-369/96)