I can't find a way in the web interface to do it and the API appears to have incomplete data. I was able to download a dump and parse through it and create a CSV with the file name and the license URL.
Here is the script [Github] I threw together**
def __init__(self): self.result = 
def triple(self, s, p, o): self.result.append((s, p, o))
def rdfToPython(s, base=None):
sink = Sink()
return rdfxml.parseRDF(s, base=None, sink=sink).result
PATH = r"C:\Users\John\Desktop\ckan-rdf"
csv_file = open("licenses.csv", 'w')
writer = csv.writer(csv_file)
for file_name in os.listdir(PATH):
with open(os.path.join(PATH, file_name)) as f:
s_rdf = f.read()
pyth = rdfToPython(s_rdf)
print "Error Parsing: " + file_name
for t in pyth:
if t == u"<http://purl.org/dc/terms/rights>":
licsn = t[1:-1]
** I don't consider this to be a complete solution as the library I used threw several errors when parsing the RDF files, unless you have a good understanding of the licenses the URLs are almost useless, and my knowledge of the RDF format is very poor (I probably missed things)
You can download the CSV file by clicking this button in the upper left hand corner.