[9][10] After graduating, Weiser served as law clerk to Judge David Ebel of the Tenth Circuit Court of Appeals from September 1994 to August 1995.

[12][1][13] From June 2011 through July 2016, Weiser served as the fifteenth dean of the law school,[14][15] and he was named one of the National Jurist's most influential leaders in legal education.

[16] Through the Silicon Flatirons Center, Weiser developed a range of programs to build up CU Boulder's support for entrepreneurship and has linked it to the local startup community.

[23] In 2010, President Obama named him senior advisor for technology and innovation to the National Economic Council Director, and he participated in a series of policy initiatives.

[28] In the 2022 Colorado Attorney General election, Weiser was re-elected for a second term, defeating Republican challenger John Kellner and winning over 54% of votes cast.

[5] On October 23, 2019, Weiser released the results of an eight-month investigation revealing that 43 Catholic clergy were credibly accused of sexually abusing at least 166 children throughout the state of Colorado since 1950.

[30] On December 1, 2020, Weiser's final report revealed that there were an additional 9 credibly accused clergy and 46 alleged victims in both in the Archdiocese of Denver and its suffragan Diocese of Pueblo.