As one of his first acts as president, Barack Obama dismissed former-president Bush’s rules governing the federal funding of stem cell research. And on Monday, the National Institute of Health issued its new set of replacement guidelines.

The new rules overturn the ban on creating new cell lines, establish a registry of stem cell lines approved for federally funded research, and create a system where stem cell lines approved under previous guidelines can petition for federal funding under the new regime.

That last note proved contentious when early drafts of the plan began circulating in April. Those early drafts required a donor consent process so lengthy and explicit that older stem cell lines created under less stringent constraints would become disqualified from use in federally funded programs.

Under Monday’s rules, older stem cell lines can gain approval for use in federally funded programs by applying for review by the Advisory Committee to the Director of the National Institute of Health. The Committee has already vowed to judge the applicants by whether or not they conformed to the spirit, not the letter, of the new law, thus providing an avenue for most previously created lines to secure approval.

The new rules also allow for the creation of novel stem cell lines, so long as the cells were originally created for in vitro fertilization, and the donors specifically sign off on the use of their discarded cells. Before signing the release, doctors must inform potential donors that their embryos may be used in experiments, and that the donors will not receive any money or special benefits if the experiments that use their embryos produce a commercially available treatment.

Some scientists expressed concerns that the new rules still block federal funding for stem cells lines created specifically for research purposes, but most are excited by the potential of an expanded pool of research subjects.

To brush up on the ins and outs of cutting edge stem cell research, check out our Essential Guide to Stem Cells.