1. I consulted Is there subject missing in as-clause? but here is only the subject missing? In that other question, another as was omitted, but in this question, only one as is necessary?

No court may accept a majority verdict unless it appears that the jury has had such period of time for deliberation as ♦ seems to the court reasonable, according to the nature and complexity of the case...

Source: p 156, How the Law Works, Gary Slapper

2. What's this omission called? Also, is there an as-clause here?

3. The ♦ is my addition. Should there be a pronoun it there, the antecedent of which is such period of time for deliberation?

4. Yet why omit the it? Wouldn't a reader be confused, detained, and frustrated?

Here's another example from p 117, How the Law Works, Gary Slapper:

The Lords ruled that the convention against allowing any reference to Hansard when interpreting statutes should be relaxed, so as to permit reference to parliamentary materials where: ... (2) the material relied upon one or more statements by a minister or other promoter of the Bill, together with such other parliamentary material as was necessary to understand such statements and their effect;

Update: I didn't realise user StoneyB's comment below: as here is part of the such...as construction.

1. I consulted Is there subject missing in as-clause? but here is only the subject missing? In that other question, another as was omitted, but in this question, only one as is necessary?

No court may accept a majority verdict unless it appears that the jury has had such period of time for deliberation as ♦ seems to the court reasonable, according to the nature and complexity of the case...

Source: p 156, How the Law Works, Gary Slapper

2. What's this omission called? Also, is there an as-clause here?

3. The ♦ is my addition. Should there be a pronoun it there, the antecedent of which is such period of time for deliberation?

4. Yet why omit the it? Wouldn't a reader be confused, detained, and frustrated?

Here's another example from p 117, How the Law Works, Gary Slapper:

The Lords ruled that the convention against allowing any reference to Hansard when interpreting statutes should be relaxed, so as to permit reference to parliamentary materials where: ... (2) the material relied upon one or more statements by a minister or other promoter of the Bill, together with such other parliamentary material as was necessary to understand such statements and their effect;

Update: I didn't realise user StoneyB's comment below: as here is part of the such...as construction.

1. I consulted Is there subject missing in as-clause? but here, is only the subject missing? In that other question, another as was omitted, but in this question, only one as is necessary?

No court may accept a majority verdict unless it appears that the jury has had such period of time for deliberation as ♦ seems to the court reasonable, according to the nature and complexity of the case...

Source: p 156, How the Law Works, Gary Slapper

2. What's this omission called? Also, is there an as-clause here?

3. The ♦ is my addition. Should there be a pronoun it there, the antecedent of which is such period of time for deliberation?

4. Yet why omit the it? Wouldn't a reader be confused, detained, and frustrated?

Here's another example from p 117, How the Law Works, Gary Slapper:

The Lords ruled that the convention against allowing any reference to Hansard when interpreting statutes should be relaxed, so as to permit reference to parliamentary materials where: ... (2) the material relied upon one or more statements by a minister or other promoter of the Bill, together with such other parliamentary material  as was necessary to understand such statements and their effect;

Update: I didn't realise user StoneyB's comment below: as here is part of the such...as construction

1. I consulted Is there subject missing in as-clause? but here is only the subject missing? In that other question, another as was omitted, but in this question, only one as is necessary?

No court may accept a majority verdict unless it appears that the jury has had such period of time for deliberation as ♦ seems to the court reasonable, according to the nature and complexity of the case...

Source: p 156, How the Law Works, Gary Slapper

2. What's this omission called? Also, is there an as-clause here?

3. The ♦ is my addition. Should there be a pronoun it there, the antecedent of which is such period of time for deliberation?

4. Yet why omit the it? Wouldn't a reader be confused, detained, and frustrated?

Here's another example from p 117, How the Law Works, Gary Slapper:

The Lords ruled that the convention against allowing any reference to Hansard when interpreting statutes should be relaxed, so as to permit reference to parliamentary materials where: ... (2) the material relied upon one or more statements by a minister or other promoter of the Bill, together with such other parliamentary material  as was necessary to understand such statements and their effect;

Update: I didn't realise user StoneyB's comment below: as here is part of the such...as construction.

1. I consulted Is there subject missing in as-clause? but here, is only the subject missing? In that other question, another as was omitted, but in this question, only one as is necessary?

No court may accept a majority verdict unless it appears that the jury has had such period of time for deliberation as ♦ seems to the court reasonable, according to the nature and complexity of the case...

Source: p 156, How the Law Works, Gary Slapper

2. What's this omission called? Also, is there an as-clause here?

3. The ♦ is my addition. Should there be a pronoun it there, the antecedent of which is such period of time for deliberation?

4. Yet why omit the it? Wouldn't a reader be confused, detained, and frustrated?

Here's another example from p 117, How the Law Works, Gary Slapper:

The Lords ruled that the convention against allowing any reference to Hansard when interpreting statutes should be relaxed, so as to permit reference to parliamentary materials where: ... (2) the material relied upon one or more statements by a minister or other promoter of the Bill, together with such other parliamentary material as was necessary to understand such statements and their effect;

1. I consulted Is there subject missing in as-clause? but here, is only the subject missing? In that other question, another as was omitted, but in this question, only one as is necessary?

No court may accept a majority verdict unless it appears that the jury has had such period of time for deliberation as ♦ seems to the court reasonable, according to the nature and complexity of the case...

Source: p 156, How the Law Works, Gary Slapper

2. What's this omission called? Also, is there an as-clause here?

3. The ♦ is my addition. Should there be a pronoun it there, the antecedent of which is such period of time for deliberation?

4. Yet why omit the it? Wouldn't a reader be confused, detained, and frustrated?

Here's another example from p 117, How the Law Works, Gary Slapper:

The Lords ruled that the convention against allowing any reference to Hansard when interpreting statutes should be relaxed, so as to permit reference to parliamentary materials where: ... (2) the material relied upon one or more statements by a minister or other promoter of the Bill, together with such other parliamentary material as was necessary to understand such statements and their effect;

Update: I didn't realise user StoneyB's comment below: as here is part of the such...as construction