The UK Government through Public Health England (PHE) has recently updated its guidance on the Management of HIV infected Healthcare Workers (HCWs) who perform exposure prone procedures in January 2014.

 The guidance states that,  "All new HCWs employed or starting training (including students) in a clinical care setting, either for the first time or returning to work in the NHS should undergo standard health checks which will include being offered an HIV antibody test. HCWs who will perform EPPs must be tested for HIV antibody HCWs who apply for a post or training which requires the performance of EPPs and who decline to be tested for HIV, hepatitis B and hepatitis C should not be cleared for EPP work".  In addition, HIV infected HCWs must meet certain criteria before they can perform EPPs. The guidance is available online @ https://www.gov.uk/government/publications/hiv-infected-healthcare-workers-and-exposure-prone-procedures

The current recommended in the UK is to use fourth generation assays which tests for HIV antibody AND p24 antigen simultaneously and not third generation (antibody only detection) assays.

The legal status is different in every country. Please tell me the country you are interested in and I let you know. I am a former physician who is HIV positive. If you or people you know face any problem with stigma regarding employment as being an HIV positive physician, please let me know and I route those individuals to organizations or people will help them. Below you find the link to a book that I wrote under pseudonym.

HIV is tested by non-specific proteins (including p24, gp120..all its 9 proteins are non-specific) or their immunereaction, which explains false-positivity and/or conversion rates. Diagnostic criteria are variable across the world i.e. less stringent in Africa, more in Europe/US. HIV is the smartest 'virus' ever - it has predetermined determinants, completely different epidemiologic and 'viral' features in the North and South. 'Gold-standard' diagnostic methods have been questioned ever since its 'emergence'. Throughout the last 30 years, the HIV-AIDS hypothesis had become a self-fulfilling prophecy, rather than a scientific one. The hypothesis has been going through critical exploration including fundamental questions and scientific reappraisal - NONE of which remain answered. References below, only to mention few. 

Article AIDS proposal. Group for the Scientific Reappraisal of the H...

Article Expression of endogenous HIV-1 crossreactive antigens within...

Data AIDS since 1984: No evidence for a new, viral epidemic – not...

In Portugal, no one is obliged to test HIV seropositivity. HCWs are offered to make the test, although being HIV positive can´t be a used as an argument to dismiss any worker. In the few cases of an HIV postive physician, they self restrained of invasive procedures, like surgery. These doctors are still working in the field of medicine, in consulting or administrative positions.

Regarding Woldemanuel answer, I wonder how such cepticism about HIV is still defensable nowadays... just a few remarks: how can we explain the clinical improvementof AIDS patients, tightly connected to curbing viral load to undetectability associated with antiretroviral therapy? How can we explain the astonishing effect on AIDS mortality since protease inhibitors introduction?

Selective reading of the scientific literature can dismiss evidence that contradicts one theses. That's definetely the case of Duesberg, who inspired South African AIDS policy under Mbeki's rule and that can be accountable  for over 330,000 excess AIDS deaths and many preventable infections, including those of infants (Chigwedere P, Seage GR, Gruskin S, Lee TH, Essex M (October 2008). "Estimating the Lost Benefits of Antiretroviral Drug Use in South Africa". Journal of acquired immune deficiency syndromes (1999) 49 (4): 410)