The Obligation Worker From a Temporary Employment Agency

There is a law in Israel that is called "The Obligation of One Who Requests the Services of a Contractor for the Rights of Workers." The law’s main idea is that the one who hires a worker through a temporary employment agency has the obligation to ensure that the worker receives the rights that are due to him by law. We will evaluate the law from a halachic basis. The main question is, assuming that a worker has certain rights that he can demand of an employer, is the one who receives a worker from a temporary employment agency (the mazmin) obligated to provide those rights. We will distinguish between an agency that actually pays the worker and one who arranges the employment, yet the mazmin pays the worker directly.
The gemara (Bava Metzia 76a) relates to a case where a middleman hires a worker on behalf of an employer. The gemara distinguishes between a case where the middleman tells the worker, "Your salary is the employer’s responsibility" and one where he says, "Your salary is my responsibility." In the latter case, the gemara says that if details were not stipulated, the "employer" has to reimburse the middleman who pays the worker according to the benefit he received. The gemara does not discuss the matter of the relationship between the mazmin and the worker. To the contrary, in the case that the middleman says he will pay, it says that the mazmin does not directly pay the worker.
This idea also emerges from the following gemara (Bava Metzia 110b-111a): "If one tells his friend, ‘Go hire workers for me,’ the two of them do not violate bal talin (delayed payment of salary), one because he did not hire the worker and one because the salary is not his responsibility. What case is it referring to? If he said, ‘Your salary is my responsibility,’ the payment is his ... rather it must be talking about a case where he said, ‘Your pay is the employer’s responsibility.’" We see from the gemara that when the mazmin does not pay on time, he does not violate bal talin. From here Harav Uri Sadan ("The Employment of Workers of a Temporary Employment Agency," Techumin XXVI, starting p. 394) concludes that there are no work relations between the mazmin and the worker, and therefore there are no related obligations. However, this is not a clear conclusion, as it is possible that there is a difference between the matter of bal talin and other legal responsibilities. Indeed we have found special limitations to the violation of bal talin. For example, the gemara (ibid.) says that merchants of the market in Sura are not bound by bal talin because it is known that they wait until the day of the market to pay. So we see that it is possible that one has a responsibility to pay even if there is no bal talin for failing to do so on time.