The strict parameter to JSONDecoder() is undocumented and is confusing 
because someone might assume it has something to do with the encoding 
parameter or the general handling of parsing errors (which it doesn't).

As far as I can determine by reading the source, strict determines 
whether or not JSON strings are allowed to contain literal newlines in 
them or not.  For example (note: loads() passes its parameters to 
JSONDecoder):

>>> s = '{"test":"Hello\nWorld"}'
>>> print(s)
{"test":"Hello
World"}
>>> json.loads(s)
Traceback (most recent call last):
...
  File "/tmp/lib/python3.0/json/decoder.py", line 159, in JSONString
    return scanstring(match.string, match.end(), encoding, strict)
ValueError: Invalid control character at: line 1 column 14 (char 14)

>>> json.loads(s,strict=False)
{'test': 'Hello\nWorld'}
>>> 

Note in this last example how the result has the literal newline 
embedded in it when strict is set False.