washington president barack obama leave office jan. 20 eight years several major initiatives still hang legal balance mean u.s. court successor play major role shape legacy ongoing legal challenge republican-governed state business group target obama signature healthcare law plan combat climate change key immigration initiative transgender right policy net neutrality internet rule overtime pay workers matter case await rule trial judge regional federal appeal court could bind u.s. supreme court unlikely get winner tuesday election pit democrat hillary clinton republican donald trump swear unless u.s. senate change course confirm obama nominee appellate court judge merrick garland fill vacant ninth seat ideologically split supreme court next president would responsible select new justice could cast decide vote case supreme court already agree decide major transgender right case obama administration back female-born transgender high school student name gavin grimm identify male sue 2015 win right use school boys bathroom rule also could resolve similar litigation around country due end june another transgender right case number state challenge obama administration may guidance public school nationwide let transgender students use bathrooms choice federal judge block policy august litigation continue obama much presidency face republican-controlled congress hostile legislative initiatives often bypass lawmakers use executive power advance policy goals despite majorities house congress republicans refuse govern instead litigious republican party rush court partisan lawsuits white house spokesman eric schultz say challenge obama vow fight unless successor change course new administration rescind policies respect bound place happily direct energies elsewhere add republican texas attorney general ken paxton help spearhead various legal challenge obama clinton back obama white house bid could expect leave place even expand initiatives defend court trump elect could quickly reverse obama executive order promise undo large-scale regulations like power plant emissions rule could complicate stroke pen say sean donahue lawyer represent environmental group back obama administration climate rule know clean power plan trump would undergo new lengthy rule-making process accord legal experts case big potential long-term impact challenge state industry group obama clean power plan would curb greenhouse emissions mainly coal-fired power plant rule important legacy issue obama also vital u.s. obligations last year international climate change treaty federal appeal court hear oral arguments september rule due months case likely go supreme court appeal supreme court put regulations hold february litigation continue republicans conservative group launch numerous challenge 2010 affordable care act know obamacare supreme court 2012 2015 issue rule preserve obama top legislative achievement another republican-led legal challenge make way court administration appeal district court judge may decision federal government spend billions dollars provide subsidies obamacare help individuals buy policies private insurers without congressional approval separately administration seek federal court texas revive obama 2014 executive action protect millions immigrants country illegally deportation give work permit plan challenge texas state bar court supreme court split 4-4 june leave place low court order block plan october decline revisit rule obama regulations target business group federal appeal court june uphold obama landmark net neutrality rule bar internet service providers obstruct slow consumer access web content case remain appeal september state business group file legal challenge administration rule extend mandatory overtime pay millions workers rule due obama leave office graphic court weigh obama legacy fate obama legacy initiatives hand court successor