Use of Le Subjonctif Présent vs Passé

Question

Je te crois à moins que tu ne m'aies menti.I believe you unless you lied to me.In this example the French is in Le Subjonctif Présent but the English translation is in the past tense (present tense would be "unless you are lying to me"). Why is the French not "Je te crois à moins que tu ne m'aies eu menti"?

Accepted Answer

I might be missing something in the question and quoted phrases but “ m’aies menti “ is the past subjunctive of ‘mentir’.
In the subjunctive present, it would simply be ‘ me mentes..’ .
Only present and past subjunctive are used in modern French speech (and pretty much the same for writing).
With only 2 tenses in this context in French, and mostly the present subjunctive used, differences between tenses in the translations are to be expected when the French subjunctive is used. 
‘ m’aies eu menti ’ would use 2 consecutive past participles. I don’t think this can ever be correct, but maybe I have forgotten something. My understanding is that a conjugated verb followed by another verb, would require the infinitive, not another past participle. 
 
See links
https://www.wordreference.com/conj/frverbs.aspx?v=mentir 
https://www.lawlessfrench.com/verb-conjugations/mentir/ 
https://www.lawlessfrench.com/grammar/infinitive/

Answer

The past subjunctive is only used when the speaker wants to stress the sequence of events. Otherwise, the present subjunctive is the default.